Heat-stabilized acrylate elastomer composition and process for its production

ABSTRACT

Polyamide-filled acrylate copolymer compositions comprising a continuous acrylate copolymer phase and a discontinuous polyamide phase are produced by a melt mixing process. When crosslinked with diamine curatives the polyamide-filled acrylate copolymer compositions exhibit enhanced resistance to heat aging compared to carbon black-reinforced acrylate copolymer compositions.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority from U.S. Patent Application Ser. No.61/499,590, filed on Jun. 21, 2011, which is incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

The present invention is directed to an amine curable elastomercomposition, a process for producing a thermoset acrylate elastomercomposition having enhanced heat-aging performance, and to articlesformed from the thermoset elastomer composition.

BACKGROUND OF THE INVENTION

Polyacrylate elastomers are well-known synthetic rubbers formed bypolymerization of alkyl acrylates. The polyacrylate elastomers may bepolyacrylates that contain only copolymerized alkyl acrylate units, forexample copolymerized units of methyl acrylate and butyl acrylate.Alternatively, they may be alkyl acrylate copolymers that containadditional copolymerized monomers, such as ethylene, and cure sitemonomers such as chlorovinyl ether, monomers that contain carboxylgroups, and/or epoxide containing monomers. The raw polymers, also knownas gums or gum rubbers, may be cured with a wide variety of curatives,depending on the cure site monomers. Some acrylate elastomers may becured with metal soaps such as sodium or potassium stearate, incombination with sulfur, a sulfur donor, a tertiary amine, or aquaternary amine salt. Epoxides, isocyanates, and polyols may also beused in certain cases. Polyamines, specifically diamines, are effectivecuratives for polyacrylates comprising amine-reactive cure sites. Ofthese curatives, diamines or diamine generators are often preferredbecause the cured polymers produced exhibit enhanced heat agingresistance. Therefore, diamine curable acrylate elastomers are sometimesreferred to as “High Temperature” acrylate elastomers. Examples ofcommercially available acrylate elastomers include Vamac® ethyleneacrylic elastomers manufactured by E. I. du Pont de Nemours and Company,HyTemp® elastomers, manufactured by Zeon Chemicals L.P, and Noxtite® ACMacrylic rubber available from Unimatec Co., Ltd.

In view of their excellent oil resistance, polyacrylate elastomers arewidely used in the manufacture of automotive parts, such as automotiveboots, ignition cable jacketing and hoses.

Resistance to heat aging is a particularly desirable property in rubberparts that are used in under the hood automotive applications, e.g.hoses, gaskets, and seals. Because such parts may be exposed totemperatures in excess of 180° C. for periods of several hours on aregular basis, degradation of physical properties through oxidativeembrittlement can occur. In acrylate rubbers, a reduction inextensibility and an increase in hardness and modulus of the acrylaterubber article often result. Such effects are disclosed for example inZeon Chemicals L.P., HyTemp® Technical Manual, Rev. 2009-1, p. 59-61(2009). Methods to enhance heat age resistance of polyacrylate rubbershave involved attempts to increase the oxidative stability of thepolymer by manipulation of the monomer types that comprise thecopolymerized units in the polymer backbone including the monomer ratio.In theory, such alterations can provide modified polymer architecturesthat exhibit increased stability. More effective antioxidants have alsobeen sought. However, there is still a need to improve the hightemperature resistance of acrylate elastomers.

Although it is known that the presence of fillers can have an adverseeffect on high temperature stability of acrylate elastomers, thepresence of fillers in elastomer formulations (also referred to in theart as elastomer compounds) is generally necessary for reinforcement anddevelopment of certain physical properties such as tensile strength andmodulus in cured (i.e. crosslinked) compositions and articles comprisingthe cured compositions. Carbon black is the most widely used filler dueto its excellent reinforcement properties and low cost. Other examplesof fillers that are commonly used in acrylate elastomers includehydrated alumina, calcium carbonate, barium sulfate, titanium dioxide,magnesium silicate, kaolin clay, and silica. All these fillers adverselyaffect heat aging of cured acrylate elastomer compositions and articles.

It has been postulated that fillers accelerate heat aging ofpolyacrylate elastomers by facilitating transport of oxygen to thepolymer-filler interface. This leads to an increased rate of formationof free radicals at such locations through oxidative reactions. The freeradicals generated in this manner promote crosslinking reactions,thereby resulting in eventual embrittlement of the elastomer.Reinforcing grades of carbon black such as N330 and N550 areparticularly effective at facilitating transport of oxygen because theycontain pores that may transport air. However, even non-porous fillerscreate interfacial regions between the solid filler particles and theelastomer. Few polymer chains reside in such interfacial regions andconsequently diffusion of air may be enhanced. Thus, exposure of theelastomer to air is believed to be greater in filled polyacrylateelastomers compared to polyacrylate elastomers that are free of filler.

As the reinforcing power of a filler increases, e.g., the ability of thefiller to increase Shore A hardness of a cured acrylate elastomercomposition, the tendency of that filler to lower resistance of theacrylate elastomer to the deleterious effects of hot air aging alsoincreases. Such effects are disclosed for a range of carbon black typesby Unimatec Chemicals Germany in a publication entitled Noxtite ACM(basic), January 2007, pp. 56-57. It would be desirable to haveavailable an alternative filler that permits the attainment of goodelastic properties such as compression set resistance and tensileelongation to break in the cured, filled elastomer and further providesthe advantages of filler reinforcement (i.e. high tensile strength,modulus and Shore A hardness), but does not promote oxidativedegradation at high temperatures (i.e. 160° C. or greater).

It has now been found that it is possible to produce cured acrylateelastomer compositions of high hardness, strength, and elasticity, thatexhibit excellent heat aging resistance through use of polyamide as afiller.

A number of acrylate rubber-polyamide blend compositions have beendisclosed in the prior art. For example, it is known to add uncuredacrylate elastomers (i.e. gums) to polyamides to form toughenedthermoplastic compositions. U.S. Pat. No. 4,174,358 discloses the use ofvarious uncured acrylate elastomers or ethylene based thermoplasticresins comprising up to 95 mole percent ethylene, such asethylene/methyl acrylate/monoethyl maleate/ethylene dimethacrylatetetrapolymers or ionomers of ethylene/methyl acrylate/monoethyl maleateterpolymers, as toughening additives for polyamides. The polyamidecomponent in such compositions comprises the continuous polymer matrixand the uncured acrylate elastomer is a minor additive. U.S. Pat. No.5,070,145 discloses thermoplastic blends of polyamides with ethylenecopolymers comprising copolymerized units of dicarboxylic acidanhydrides and optionally alkyl(meth)acrylates. U.S. Pat. No. 7,544,757discloses that blends of ethylene-alkyl acrylate polymers may be blendedat levels up to 30% by weight in polyamide to produce toughenedpolyamide compositions.

Blends of uncured ethylene acrylic elastomers, polyamides and powderedmetals are disclosed in Japanese Patent 2001-1191387.

U.S. Pat. No. 3,965,055 discloses vulcanizates prepared from a blend ofrubber and 2 wt. % to 10 wt. % of a crystalline fiber-formingthermoplastic, wherein the thermoplastic is dispersed in the rubbercomponent in particles not greater than 0.5 micron in cross section witha length to diameter ratio greater than 2. The high aspect ratio of thethermoplastic particles enables pressureless curing without voidformation.

Japanese Patent Application Publication H10-251452 discloses adispersion of polyamide particles in a hydrogenated nitrile rubber(HNBR) matrix wherein a compatibilizing polymer that may be an ethylenecopolymer or an acrylate elastomer is also present. The compatibilizingpolymer is ionically crosslinked by metal oxide during mixing with theHNBR and polyamide which prevents the acrylate elastomer from forming acontinuous phase. The HNBR component is then cured with a peroxide orwith sulfur.

U.S. Pat. No. 6,133,375 discloses blends of functionalized rubbers withthermoplastics in which the thermoplastic component is dispersed in therubber phase. Following addition of a curative for the rubber, thecomposition is crosslinked to produce a vulcanized article. Examples offunctionalized rubbers which are disclosed include acrylic rubbers suchas nitrile-butadiene rubber, hydrogenated nitrile-butadiene rubber,epichlorohydrin rubber, and rubbers on which reactive groups have beengrafted, such as carboxylated nitrile-butadiene rubber. Thermoplasticsthat are disclosed include polyetherester block copolymers,polyurethanes, polyamides, polyamide ether or ester block copolymers,and mixtures of polyamides and polyolefins. In the latter case,ethylene-alkyl acrylate copolymers comprising grafted or co-polymerizedmaleic anhydride, glycidyl methacrylate, or (meth)acrylic acid units maybe used to compatibilize the polyamide-polyolefin blend.

U.S. Pat. No. 4,694,042 discloses an elastomeric thermoplastic moldingmaterial containing a coherent phase of polyamide and crosslinkedelastomeric polyacrylate core shell polymers.

U.S. Pat. No. 4,275,180 discloses blends of thermoplastic polymers withacrylate rubbers, the blends being crosslinked or crosslinkable byradiation or peroxide. Fillers may be used in amounts of up to 40% byweight of the composition.

U.S. Patent Application 2006/0004147 discloses blends of elastomers, forexample acrylate elastomers, with thermoplastic polymers such aspolyamides, in which both polymers are coupled and crosslinked by freeradicals, e.g., by electron beam radiation. The compositions maycomprise a continuous phase of thermoplastic with dispersed crosslinkedelastomer particles, or a continuous crosslinked elastomer phase withdispersed crosslinked particles of what was initially thermoplastic.

U.S. Pat. No. 8,142,316 discloses cured blends of elastomers andthermoplastics for use in power transmission belts. The elastomer may bean ethylene acrylic elastomer, and the thermoplastic may be a polyamide.Free radical curatives are disclosed as curing agents.

It is also known to form dynamically cured thermoplastic compositionshaving a polyamide matrix continuous phase and a cured acrylate rubberphase that is present in the form of discrete particles. Thermoplasticelastomeric compositions comprising blends of polyamide and ionicallycrosslinked ethylene acrylic rubber are disclosed in U.S. Pat. No.4,310,638. U.S. Pat. Nos. 5,591,798 and 5,777,033 disclose thermoplasticelastomer compositions comprising a blend of polyamide resins andcovalently-crosslinked acrylate rubber.

U.S. Pat. No. 7,608,216 and U.S. Patent Application Publication2006/0100368 disclose compositions prepared by admixing an uncuredthermoset elastomer, for example an acrylate elastomer, with athermoplastic polymer or another uncured (gum) elastomer. Techniquessuch as fractional curing, partial dynamic vulcanization, or the use ofhigh performance reinforcing fillers are disclosed to increase the greenstrength of the uncured or partially cured compound. The admixedcompositions may be subsequently crosslinked with a curing agent for theelastomer component.

Polyacrylate rubber-polyamide blend compositions disclosed in ZeonChemicals L.P., HyTemp® Technical Manual, Rev. 2009-1, p. 46 (2009) aresaid to improve impact strength of plastics. They may also be used toproduce thermoplastic elastomers.

It has now been surprisingly found that when a dispersion of polyamideparticles replaces all or a significant portion of a conventionalparticulate reinforcing agent in a continuous polyacrylate elastomermatrix, the resultant compositions, when cured with an amine curativesystem, exhibit enhanced resistance to physical property loss duringheat aging. In addition, such compositions maintain excellent tensilestrength, modulus, hardness, and elastic properties such as compressionset and elongation at break that characterize compositions containingconventional reinforcing fillers.

SUMMARY OF THE INVENTION

The present invention is directed to a polyimide-filled acrylatecopolymer composition comprising

-   -   A. a polymer blend composition comprising    -   1. 40 to 90 wt. % of one or more amorphous acrylate copolymers        comprising        -   a) at least 50 wt. %, based on the total weight of the            amorphous acrylate copolymer, of polymerized units of at            least one monomer having the structure

-   -   -   -   Where R¹ is H or C₁-C₁₀ alkyl and R² is C₁-C₁₂ alkyl,                C₁-C₂₀ alkoxyalkyl, C₁-C₁₂ cyanoalkyl, or C₁-C₁₂                fluoroalkyl, and

        -   b) 0.3 mole percent-1.0 mole percent copolymerized units of            a cure site monomer selected from the group consisting of            unsaturated carboxylic acids, anhydrides of unsaturated            carboxylic acids, unsaturated epoxides, and mixtures of two            or more thereof; and

    -   B. 10-60 wt. % of one or more polyamides having a melting peak        temperature of at least 160° C.;

    -   wherein i) the polymer blend has a green strength of less than        about 2 MPa as determined according to ASTM D6746-10, ii) the        one or more polyamides are present as a discontinuous phase in        the polymer blend composition, and iii) the weight percentages        of the one or more amorphous acrylate copolymers and one or more        polyamides are based on the combined weight of the one or more        amorphous acrylate copolymers and one or more polyamides in the        polymer blend composition.

The present invention is also directed to a curable polyamide-filledacrylate copolymer composition comprising

-   -   A. a polymer blend composition comprising        -   1. 40 to 90 wt. % of one or more amorphous acrylate            copolymers comprising            -   a) at least 50 wt. %, based on the total weight of the                amorphous acrylate copolymer, of polymerized units of at                least one monomer having the structure

-   -   -   -   -   Where R¹ is H or C₁-C₁₀ alkyl and R² is C₁-C₁₂                    alkyl, C₁-C₂₀ alkoxyalkyl, C₁-C₁₂ cyanoalkyl, or                    C₁-C₁₂ fluoroalkyl, and

            -   b) copolymerized units of a cure site monomer selected                from the group consisting of unsaturated carboxylic                acids, anhydrides of unsaturated carboxylic acids,                unsaturated epoxides, and mixtures of two or more                thereof; and

    -   2. 10-60 wt. % of one or more polyamides having a melting peak        temperature of at least 160° C.;        -   wherein the green strength of the polymer blend composition            is less than about 2 MPa, as determined in accordance with            ASTM D6746-10, and iii) the weight percentages of the one or            more amorphous acrylate copolymers and one or more            polyamides are based on the combined weight of the amorphous            one or more acrylate copolymers and one or more polyamides            in the polymer blend composition; and

    -   B. an amine curative.

The invention is also directed to a process for production of apolyimide-filled acrylate copolymer composition, the process comprisingthe steps

-   -   A. providing a polymer blend composition comprising        -   1. 40 to 90 wt. % of one or more amorphous acrylate            copolymers comprising            -   a) at least 50 wt. %, based on the total weight of the                amorphous acrylate copolymer, of polymerized units of at                least one monomer having the structure

-   -   -   -   -   Where R¹ is H or C₁-C₁₀ alkyl and R² is C₁-C₁₂                    alkyl, C₁-C₂₀ alkoxyalkyl, C₁-C₁₂ cyanoalkyl, or                    C₁-C₁₂ fluoroalkyl; and

            -   b) copolymerized units of a cure site monomer selected                from the group consisting of unsaturated carboxylic                acids, anhydrides of unsaturated carboxylic acids,                unsaturated epoxides, and mixtures of two or more                thereof; and

        -   2. 10-60 wt. % of one or more polyamides having melting peak            temperatures of at least 160° C.;

        -   wherein i) the one or more polyamides are present as a            discontinuous phase in the polymer blend composition and ii)            the weight percentages of the one or more amorphous acrylate            copolymers and one or more polyamides are based on the            combined weight of the one or more amorphous acrylate            copolymers and one or more polyamides in the polymer blend            composition;

    -   B. mixing the polymer blend composition at a temperature above        the melting peak temperatures of the one or more polyamides to        disperse the one or more polyamides within the one or more        amorphous acrylate copolymers, thereby forming a        polyamide-filled acrylate copolymer composition; and

    -   C. cooling the polyamide-filled acrylate copolymer composition        to a temperature below the crystallization peak temperatures of        the one or more polyamides, thereby forming a polyamide-filled        acrylate copolymer composition that i) comprises a continuous        amorphous acrylate copolymer phase and a discontinuous polyamide        phase and ii) has a green strength of less than about 2 MPa as        determined according to ASTM D 6746-10.

The invention is also directed to a process for preparing a curablepolyamide-filled acrylate copolymer composition which comprises thesteps of providing a polyamide-filled acrylate copolymer compositionprepared by the above-described process and adding an amine curative tothe polyamide-filled acrylate copolymer composition.

The invention is further directed to a process for preparing an acrylatecopolymer elastomer composition comprising the steps of

-   -   A. providing a polyamide-filled acrylate copolymer composition        that has been prepared by a process comprising the steps        -   1. providing a polymer blend composition comprising            -   a. 40-90 wt. % of one or more amorphous acrylate                copolymers comprising i) at least 50 wt. %, based on the                total weight of the copolymer, of copolymerized units of                a monomer having the structure

-   -   -   -   -   Where R¹ is H or C₁-C₁₀ alkyl and R² is C₁-C₁₂                    alkyl, C₁-C₂₀ alkoxyalkyl, C₁-C₁₂ cyanoalkyl, or                    C₁-C₁₂ fluoroalkyl, and ii) copolymerized units of a                    cure site monomer selected from the group consisting                    of unsaturated carboxylic acids, anhydrides of                    unsaturated carboxylic acids, unsaturated epoxides,                    and mixtures of two or more thereof; and

            -   b. 10-60 wt. % of one or more polyamides having a                melting peak temperature of at least 160° C.,

            -   wherein the weight percentages of the one or more                amorphous acrylate copolymers and one or more polyamides                are based on the combined weight of the one or more                amorphous acrylate copolymers and one or more polyamides                in the polymer blend;

        -   2. mixing the polymer blend composition at a temperature            above the melting peak temperature of the one or more            polyamides to disperse the one or more polyamides within the            one or more acrylate copolymers, thereby forming a            polyamide-filled acrylate copolymer composition; and

        -   3. cooling the polyamide-filled acrylate copolymer            composition to a temperature below the crystallization peak            temperatures of the one or more polyamides, thereby forming            a polyamide-filled acrylate copolymer composition that i)            comprises a continuous acrylate copolymer elastomer phase            and a discontinuous polyamide phase and ii) has a green            strength of less than about 2 MPa as determined according to            ASTM D 6746-10;

    -   B. adding an amine curative to the cooled polyamide-filled        acrylate copolymer composition to form a curable        polyamide-filled acrylate copolymer composition; and

    -   C. curing the curable polyamide-filled acrylate copolymer        composition by exposing the curable polyamide-filled acrylate        copolymer composition to a temperature of about 160° C. to about        200° C. for about 2 to 60 minutes to form a crosslinked acrylate        copolymer elastomer composition, and optionally exposing said        crosslinked composition to post-cure heating at a temperature of        about 160° C. to about 200° C., thereby forming an acrylate        copolymer elastomer composition having a Shore A hardness of at        least 40, as determined according to ASTM D 2240-06 (1 second        reading).

The invention is further directed to a curable acrylate copolymercomposition consisting essentially of

-   -   A. a polymer blend composition comprising        -   1. 40 to 90 wt. % of one or more amorphous acrylate            copolymers comprising            -   a) at least 50 wt. %, based on the total weight of the                amorphous acrylate copolymer, of polymerized units of at                least one monomer having the structure

-   -   -   -   -   Where R¹ is H or C₁-C₁₀ alkyl and R² is C₁-C₁₂                    alkyl, C₁-C₂₀ alkoxyalkyl, C₁-C₁₂ cyanoalkyl, or                    C₁-C₁₂ fluoroalkyl, and

            -   b) copolymerized units of a cure site monomer selected                from the group consisting of unsaturated carboxylic                acids, anhydrides of unsaturated carboxylic acids,                unsaturated epoxides, and mixtures of two or more                thereof; and

        -   2. 10-60 wt. % of one or more polyamides having a melting            peak temperature of at least 160° C.;

        -   wherein i) the one or more polyamides are present as a            discontinuous phase in the polymer blend composition, ii)            the weight percentages of the one or more amorphous acrylate            copolymers and one or more polyamides are based on the            combined weight of the one or more amorphous acrylate            copolymers and one or more polyamides in the polymer blend            composition and iii) the polymer blend composition has a            green strength less than about 2 MPa;

    -   B. an amine curative; and

    -   C. a reinforcing filler, the reinforcing filler being present in        the curable acrylate copolymer composition in an amount that        causes an increase in the Shore A hardness of the cured acrylate        copolymer composition of no more than about 20 points as        compared to the Shore A hardness of a control composition that        is of identical composition but for the absence of the        reinforcing filler, wherein i) the curable acrylate copolymer        composition and control composition are formed into test        specimens of 1 mm to 2.5 mm thickness, the test specimens are        cured by exposure to a temperature of 175° C. for 10 minutes in        a closed mold at a pressure of at least 10 MPa, demolded and the        test specimens are subjected to a post cure at a temperature of        175° C. for 4 hours in a hot air oven to form post cured test        specimens, ii) Shore A hardness of the post cured acrylate        copolymer composition and the post cured control composition is        determined according to ASTM D 2240-06 (1 second reading),        and iii) the post cured acrylate copolymer composition has a        Shore A hardness greater than 40.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to compositions comprising blends ofacrylate copolymers and polyamides that, when cured with an aminecurative system, exhibit enhanced resistance to physical property lossduring heat aging. The invention is also directed to a process forpreparation of the acrylate copolymer/polyamide blend compositions, aprocess for preparation of curable acrylate copolymer/polyamide blendcompositions and a process for preparation of elastomers from thecurable acrylate copolymer/polyamide blend compositions.

It has been found that when polyamide particles largely replace carbonblack and conventional reinforcing inorganic fillers in curableamorphous acrylate copolymers (also known as acrylate copolymer gumrubbers) such that the acrylate copolymer forms a continuous phase andthe polyamide forms a discontinuous phase, the resultant compositions,when cured, exhibit surprising improvements in physical properties. Thatis, the curing process, which is also commonly referred to ascrosslinking or vulcanization, converts the polyamide-filled acrylatecopolymer composition to an acrylate copolymer elastomer compositionthat exhibits enhanced heat aging resistance compared to acrylatecopolymer elastomers that comprise carbon black or other reinforcingfillers.

The term “reinforcement” refers to an increase in the hardness andtensile strength of the cured (i.e. crosslinked) composition, relativeto the similarly crosslinked but unfilled acrylate copolymer gum rubber.In particular, a crosslinked acrylate copolymer elastomer compositionhaving a Shore A hardness (ASTM D2240-06, 1 second reading) less than 40is too soft for a large majority of acrylate copolymer elastomerapplications, and therefore may be considered insufficiently reinforced.A crosslinked acrylate copolymer composition having a tensile strengthof less than 4 MPa (ASTM D412-06, die C) is too weak for a largemajority of acrylate copolymer applications, and therefore may beconsidered to be insufficiently reinforced.

One embodiment of the invention is a curable acrylate copolymercomposition that comprises a polymer blend composition and an aminecurative. The polymer blend composition is characterized by having agreen strength of less than about 2 MPa as determined in accordance withASTM D6746-10.

The polymer blend composition comprises two polymers, an acrylatecopolymer and a polyamide. The polymer blend is referred to herein as apolyamide-filled acrylate copolymer. The acrylate copolymer component ofthe curable polyamide-filled acrylate copolymer compositions of theinvention comprises one or more amorphous acrylate copolymers. The termamorphous as used herein with reference to an acrylate copolymer means acopolymer which exhibits little or no crystalline structure at roomtemperature in the unstressed state. By amorphous is meant that theacrylate copolymer has a heat of fusion of less than 4 J/g as determinedaccording to ASTM D3418-08. The term “copolymer” as used herein refersto polymers comprising copolymerized units resulting fromcopolymerization of two or more comonomers. In this connection, acopolymer may be described herein with reference to its constituentcomonomers or to the amounts of its constituent comonomers, for example“a copolymer comprising ethylene, methyl acrylate and 3 weight % of themonoethyl ester of maleic acid”, or a similar description. Such adescription may be considered informal in that it does not refer to thecomonomers as copolymerized units; in that it does not includeconventional nomenclature for the copolymer, for example InternationalUnion of Pure and Applied Chemistry (IUPAC) nomenclature; in that itdoes not use product-by-process terminology; or for another reason. Asused herein, however, a description of a copolymer with reference to itsconstituent comonomers or to the amounts of its constituent comonomersmeans that the copolymer contains copolymerized units (in the specifiedamounts when noted) of the stated comonomers. It follows as a corollarythat a copolymer is not the product of a reaction mixture containinggiven comonomers in specific amounts, unless expressly stated in limitedcircumstances to be such.

The amorphous acrylate copolymers useful in the practice of theinvention described herein comprise copolymerized units of a) at leastone alkyl ester and/or alkoxyalkyl ester of propenoic acid and b) a curesite monomer. Examples of such suitable alkyl and alkoxyalkyl esters ofpropenoic acid include alkyl acrylates and alkoxyalkyl acrylates as wellas species wherein the propenoic acid is substituted with a C₁-C₁₀ alkylgroup. Examples of such species include alkyl methacrylates, alkylethacrylates, alkyl propacrylates, and alkyl hexacrylates, alkoxyalkylmethacrylates, alkoxyalkyl ethacryates, alkoxyalkyl propacrylates andalkoxyalkyl hexacrylates. In addition, the alkyl ester groups of thepropenoic acid esters may be substituted with cyano groups or one ormore fluorine atoms. That is, the ester group will be a C₁-C₁₂cyanoalkyl group or a C₁-C₁₂ fluoroalkyl group. The acrylate copolymersmay also comprise copolymerized units of more than one species of thealkyl esters and/or alkoxyalkyl esters, for example two alkyl acrylates.

The alkyl and alkoxyalkyl esters of propenoic acid and substitutedpropenoic acids are preferably C₁-C₁₂ alkyl esters of acrylic ormethacrylic acid or C₁-C₂₀ alkoxyalkyl esters of acrylic or methacrylicacid. Examples of such esters include methyl acrylate, methylmethacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butylmethacrylate, 2-ethylhexyl acrylate, 2-methoxyethylacrylate,2-ethoxyethylacrylate, 2-(n-propoxy)ethylacrylate,2-(n-butoxy)ethylacylate, 3-methoxypropylacrylate and3-ethoxypropylacrylate. Examples of esters that contain C₁-C₁₂cyanoalkyl and fluoroalkyl groups include cyanomethylacrylate,1-cyanoethylacrylate, 2-cyanopropylacrylate, 3-cyanopropylacrylate,4-cyanobutylacrylate, 1,1-dihydroperfluoroethyl methacrylate,1,1-dihydroperfluoroethyl acrylate, 1,1-dihydroperfluoropropylmethacrylate, 1,1-dihydroperfluoropropyl acrylate, and1,1,5-trihydroperfluorohexyl(meth)acrylate, and1,1,5-trihydroperfluorohexyl methacrylate. Preferably, the ester groupwill comprise C₁-C₈ alkyl groups. More preferably, the ester group willcomprise C₁-C₄ alkyl groups. Particularly useful alkyl acrylate estersare methyl acrylate, ethyl acrylate and butyl acrylate. Particularlyuseful alkyl methacrylate esters are methyl methacrylate. Minor amountsof unsaturated acetates such as ethenyl acetate or 3-butenyl acetate maybe incorporated into the polymer without deviating from the scope ofthis invention. By minor amounts is meant less than 1 wt. %, based onthe weight of the acrylate copolymer.

Esters that comprise comonomer units in the acrylate copolymers may begenerally represented by the formula

Where R¹ is H or C₁-C₁₀ alkyl, and R² is C₁-C₁₂ alkyl, C₁-C₂₀alkoxyalkyl, C₁-C₁₂ cyanoalkyl, or C₁-C₁₂ fluoroalkyl.

In certain embodiments, the acrylate copolymers may be derived fromcopolymerization of more than one acrylate monomer, for example a firstalkyl acrylate, a second alkyl acrylate and optionally, a monoalkylester of 1,4-butenedioic acid. Examples of such compositions includecopolymers of methyl acrylate and butyl acrylate and copolymers ofmethyl acrylate, butyl acrylate and the monoethyl ester of1,4-butenedioic acid.

The concentration of propenoic acid ester comonomers that are present inthese acrylate copolymers will be at least 50 weight percent, based onthe weight of the copolymer. Preferably, the concentration will be atleast 55 weight percent, and more preferably at least 60 weight percent.If the concentration of propenoic acid ester is below 50 wt. %, thelikelihood that some crystallinity will be present is high, for examplein polymers that are ethylene acrylate ester copolymers. Crystallinityin the acrylate copolymer diminishes the elastic properties of the curedcomposition. In addition, a high content of non-polar monomer, such asethylene, diminishes compatibility of the acrylate copolymer withpolyamide, and therefore physical properties of the cured composition,such as tensile and tear strength, will be affected.

The acrylate copolymers useful in the practice of the invention comprisecopolymerized cure site monomer units selected from the group consistingof unsaturated carboxylic acids, anhydrides of unsaturated carboxylicacids, unsaturated epoxides, and mixtures of two or more thereof. Thesecure site monomer units contain chemical groups (e.g., carboxyl andepoxy groups) that react with amines and/or other nitrogen-containingspecies, such as carbamates.

Unsaturated carboxylic acids include for example, acrylic acid andmethacrylic acid, 1,4-butenedioic acids, citraconic acid, and monoalkylesters of 1,4-butenedioic acids. The 1,4-butenedioic acids may exist incis- or trans-form or both, i.e. maleic acid or fumaric acid, prior topolymerization. Useful copolymerizable cure site monomers also includeanhydrides of unsaturated carboxylic acids, for example, maleicanhydride, citraconic anhydride, and itaconic anhydride. Preferred curesite monomers include maleic acid and any of its half acid esters(monoesters) or diesters, particularly the methyl or ethyl half acidesters (e.g., monoethyl maleate); fumaric acid and any of its half acidesters or diesters, particularly the methyl, ethyl or butyl half acidesters; and monoalkyl and monoarylalkyl esters of itaconic acid. Thepresence of these copolymerized cure site monomers produces curableacrylate copolymer compositions that exhibit good scorch safety, meaningthat the cure site reacts with amines slowly or not at all attemperatures less than about 120° C., but still permits fastcrosslinking at higher temperatures.

Examples of useful unsaturated epoxides include for example, glycidyl(meth)acrylate, allyl glycidyl ether, glycidyl vinyl ether, andalicyclic epoxy-containing (meth)acrylates.

Preferably, the acrylate copolymer gum rubber comprises at least 0.3 mol% of cure site monomer units bearing the amine reactive group, based onthe total number of moles of monomer in the copolymer, more preferablyat least 0.4 mol %, and most preferably more than 0.5 mol %. While thecure site level in the acrylate copolymer must be sufficient to producea crosslinked network during the curing and post curing process, highlevels of cure site monomer tend to negatively affect heat agingproperties of the cured compositions of the invention. Preferably, theacrylate copolymer comprises less than 1.4 mol % cure site, morepreferably less than 1.2 mol %, and most preferably less than 1.0 mol %.A preferred range for many embodiments is 0.3 mol %-1.0 mol % cure sitemonomer units. When two or more acrylate copolymers are present in theacrylate copolymer component of the polyamide-filled compositions of theinvention, the range of about 0.3 to 1.0 mol % amine reactive cure sitesapplies to the weight average of mole percent cure site in theindividual acrylate copolymers. This applies to the other mol % rangesof cure site monomer when more than one acrylate copolymer is present.

In many embodiments, the acrylate copolymers useful in the practice ofthe invention will also comprise copolymerized units of additionalcomonomers, for example ethylene and/or other olefins such as propylene,1-butene, 1-hexene, 1-octene, and the like. The olefin will be presentat a concentration of less than 50 wt. %, more preferably less than 45wt. %, and most preferably about 40 wt. % or less, based on the weightof the acrylate copolymer. Ethylene alkyl acrylate copolymer rubbershaving amine-vulcanizable groups are particularly suitable acrylatecopolymers for use in the compositions and processes described herein.An example of such a rubber is Vamac® ethylene acrylic elastomer,available from E. I. du Pont de Nemours and Company.

The acrylate copolymers useful in the practice of the invention arecurable, i.e. crosslinkable, due to the presence in the polymer chainbackbone of copolymerized monomer units that contain epoxy, carboxylicacid, carboxylic acid anhydride and/or carboxylic ester moieties. Suchchemical groups can take part in thermally-induced chemical reactions inthe presence of aromatic or aliphatic polyamines, preferably diamines.

The amorphous acrylate copolymers that are used to prepare the curablepolyamide-filled acrylate copolymer compositions of the invention arecurable gums, i.e. they are substantially uncured rubbers, and retainreactivity towards crosslinking, generally by amines and certain othernitrogen-containing reactants after blending with the polyamide. Bysubstantially uncured is meant that the unblended amorphous acrylatecopolymer has a sufficiently low viscosity to be shaped into a finishedarticle by molding or extrusion. Preferably, the Mooney viscosity (ASTMD1646, ML 1+4 at 100° C.) of the acrylate copolymer is less than 120,more preferably less than 80 and most preferably less than 40. Byretaining reactivity towards crosslinking is meant that the curablecomposition intended for production of a molded or extruded article(i.e. the composition that includes acrylate copolymer, polyamide,curative and optionally conventional filler) exhibits an increase intorque (MH-ML) when tested in a rotorless cure meter per ASTM D5289-07aat conditions of 177° C. for 24 minutes of at least 2.5 dN-m, morepreferably at least 4 dN-m, and most preferably more than 5.5 dN-m. Theacrylate copolymers are amorphous polymers, rather than crystallinethermoplastics. That is, the heat of fusion of the acrylate copolymerwill generally be less than 4 J/g as measured by ASTM D3418-08,preferably less than 2 J/g, and most preferably about 0 J/g.

Acrylate copolymers of this type may be prepared for example accordingto the procedures described in U.S. Pat. Nos. 3,904,588; 4,520,183;6,156,849, and 7,402,631.

The polymer blend composition that comprises one component of thecurable acrylate copolymer compositions described herein comprises oneor more polyamides having a melting peak temperature of at least about160° C., preferably less than 270° C. as determined in accordance withASTM D3418-08. Preferably the polyamide is solid at the curingtemperature of the acrylate elastomer, meaning that the curingtemperature is less than the melting peak temperature. While not wishingto be bound by theory, when the polyamide is not solid at the curingtemperature, curative readily diffuses into the polyamide, rendering theblend difficult to cure. Polyamide resins are well known in the art andembrace those semi-crystalline resins having a weight average molecularweight of at least 5,000 and include those compositions commonlyreferred to as nylons. Thus, the polyamide component useful in thepractice of the invention includes polyamides and polyamide resins suchas nylon 6, nylon 7, nylon 6/6, nylon 6/10, nylon 6/12, nylon 11, nylon12, polyamides comprising aromatic monomers, and polyamide blockcopolymers such as copoly(amide-ether) or copoly(amide-ester). Theresins may be in any physical form, such as pellets and particles of anyshape or size, including nanoparticles.

The viscosity of the polyamide resins can vary widely while meeting theaims of the present invention. To ensure that the polyamide becomesdispersed within a continuous phase of acrylate elastomer, it isdesirable that the polyamide have an inherent viscosity greater than 0.9dL/g, more preferably greater than 1.1 dL/g, and most preferably greaterthan 1.3 dL/g, as measured in accordance with ASTM D2857-95, using 96%by weight sulfuric acid as a solvent at a test temperature of 25° C.

In general, as the concentration of the polyamide in the acrylatecopolymer blend increases, the use of a polyamide of higher inherentviscosity becomes more desirable. In certain embodiments, a polyamidewith a high content of amine end groups, about 60 meq/Kg or greater, canbe desirable and permits the use of a low viscosity polyamide ofinherent viscosity about 0.89 dL/g. Such a high amine end group contentresults in a grafting reaction between the cure site of the acrylaterubber and the polyamide amine end groups which can help to disperse thepolyamide in the acrylate rubber. In some instances, however, use ofsuch high amine content polyamide can result in gelling of the acrylaterubber during melt mixing with the polyamide, making subsequentprocessing more difficult. Gelling of the acrylate elastomer becomesmore problematic as the concentration of polyamide in the acrylatecopolymer increases.

The polyamide resin can be produced by condensation polymerization ofequimolar amounts of a saturated dicarboxylic acid containing from 4 to12 carbon atoms with a diamine, in which the diamine contains from 4 to14 carbon atoms. To promote adhesion between the acrylate rubber and thenylon, preferably the polyamide will contain some amine end groups.Polyamide types polymerized from diacids and diamines may contain somemolecules having two amine groups. In such cases, certain combinationsof polyamide and acrylate rubber can crosslink or gel slightly so as toproduce compositions with compromised extrusion processability.Polyamide types prepared by ring opening polymerization reactions suchas nylon 6, or those based solely on aminocarboxylic acids such as nylon7 or 11 are most preferred because they avoid the possibility ofcrosslinking during blending with the acrylate rubber. Such polyamidetypes contain molecules with at most one amine group each.

Examples of polyamides include polyhexamethylene adipamide (66 nylon),polyhexamethylene azelaamide (69 nylon), polyhexamethylene sebacamide(610 nylon) and polyhexamethylene dodecanoamide (612 nylon), thepolyamide produced by ring opening of lactams, i.e. polycaprolactam,polylauriclactam, poly-11-aminoundecanoic acid, andbis(p-aminocyclohexyl)methanedodecanoamide. It is also possible to usepolyamides prepared by the copolymerization of two of the above polymersor terpolymerization of the above polymers or their components, e.g. anadipic acid isophthalic acid hexamethylene diamine copolymer.

Typically, polyamides are condensation products of one or moredicarboxylic acids and one or more diamines, and/or one or moreaminocarboxylic acids, and/or ring-opening polymerization products ofone or more cyclic lactams. Polyamides may be fully aliphatic orsemi-aromatic.

Fully aliphatic polyamides useful in practice of the present inventionare formed from aliphatic and alicyclic monomers such as diamines,dicarboxylic acids, lactams, aminocarboxylic acids, and their reactiveequivalents. A suitable aminocarboxylic acid is 11-aminododecanoic acid.Suitable lactams are caprolactam and laurolactam. In the context of thisinvention, the term “fully aliphatic polyamide” also refers tocopolymers derived from two or more such monomers and blends of two ormore fully aliphatic polyamides. Linear, branched, and cyclic monomersmay be used.

Carboxylic acid monomers comprised in the fully aliphatic polyamidesinclude, but are not limited to aliphatic carboxylic acids, such as forexample adipic acid, pimelic acid, suberic acid, azelaic acid,decanedioic acid, dodecanedioic acid, tridecanedioic acid,tetradecanedioic acid, and pentadecanedioic acid. Diamines can be chosenfrom diamines having four or more carbon atoms, including, but notlimited to tetramethylene diamine, hexamethylene diamine, octamethylenediamine, decamethylene diamine, dodecamethylene diamine,2-methylpentamethylene diamine, 2-ethyltetramethylene diamine,2-methyloctamethylenediamine; trimethylhexamethylenediamine,meta-xylylene diamine, and/or mixtures thereof.

Semi-aromatic polyamides are also suitable for use in the presentinvention. Such polyamides are homopolymers, dipolymers, terpolymers orhigher order polymers formed from monomers containing aromatic groups.One or more aromatic carboxylic acids may be terephthalic acid or amixture of terephthalic acid with one or more other carboxylic acids,such as isophthalic acid, phthalic acid, 2-methyl terephthalic acid andnaphthalic acid. In addition, the one or more aromatic carboxylic acidsmay be mixed with one or more aliphatic dicarboxylic acids.Alternatively, an aromatic diamine such as meta-xylylene diamine can beused to provide a semi-aromatic polyamide, an example of which is ahomopolymer comprising meta-xylylene diamine and adipic acid.

Block copoly(amide) copolymers are also suitable for use as thepolyamide component provided the melting peak temperature of thepolyamide block is at least 160° C. If a low softening point materialcomprises the block copoly(amide) copolymer, e.g., a polyether oligomeror a polyalkylene ether, for example, poly(ethylene oxide), then theblock polymer will be a copoly(amide-ether). If a low softening pointmaterial of the block copoly(amide) copolymer comprises an ester, forexample, a polylactone such as polycaprolactone, then the blockcopolymer will be a copoly(amide-ester). Any such low softening pointmaterials may be used to form a block copoly(amide) copolymer.Optionally, the lower softening point material of the blockcopoly(amide) copolymer may comprise a mixture, for example, a mixtureof any of the above-mentioned lower softening point materials.Furthermore, said mixtures of lower softening point materials may bepresent in a random or block arrangement, or as mixtures thereof.Preferably, the block copoly(amide) copolymer is a blockcopoly(amide-ester), a block copoly(amide-ether), or mixtures thereof.More preferably, the block copoly(amide) copolymer is at least one blockcopoly(amide-ether) or mixtures thereof. Suitable commercially availablethermoplastic copoly(amide-ethers) include PEBAX® polyether block amidesfrom Elf-Atochem, which includes PEBAX® 4033 and 6333. Most preferably,the polyamide is other than a block copoly(amide-ether) orcopoly(amide-ester). Other polyamides have generally higher melting peaktemperatures and are more effective in reinforcing the acrylateelastomer. Poly(amide-ethers) also exhibit poorer hot air aging ascompared to conventional polyamides lacking a polyether block.

Preferred polyamides are homopolymers or copolymers wherein the termcopolymer refers to polyamides that have two or more amide and/ordiamide molecular repeat units.

The polyamide component may comprise one or more polyamides selectedfrom Group I polyamides having a melting peak temperature of at leastabout 160° C., but less than about 210° C., and comprising an aliphaticor semiaromatic polyamide, for example poly(pentamethylenedecanediamide), poly(pentamethylene dodecanediamide),poly(ε-caprolactam/hexamethylene hexanediamide),poly(ε-caprolactam/hexamethylene decanediamide),poly(12-aminododecanamide), poly(12-aminododecanamide/tetramethyleneterephthalamide), and poly(dodecamethylene dodecanediamide); Group (II)polyamides having a melting peak temperature of at least about 210° C.,and comprising an aliphatic polyamide selected from the group consistingof poly(tetramethylene hexanediamide), poly(ε-caprolactam),poly(hexamethylene hexanediamide), poly(hexamethylene dodecanediamide),and poly(hexamethylene tetradecanediamide); Group (III) polyamideshaving a melting peak temperature of at least about 210° C., andcomprising about 20 to about 35 mole percent semiaromatic repeat unitsderived from monomers selected from one or more of the group consistingof (i) aromatic dicarboxylic acids having 8 to 20 carbon atoms andaliphatic diamines having 4 to 20 carbon atoms; and about 65 to about 80mole percent aliphatic repeat units derived from monomers selected fromone or more of the group consisting of an aliphatic dicarboxylic acidhaving 6 to 20 carbon atoms and said aliphatic diamine having 4 to 20carbon atoms; and a lactam and/or aminocarboxylic acid having 4 to 20carbon atoms; Group (IV) polyamides comprising about 50 to about 95 molepercent semi-aromatic repeat units derived from monomers selected fromone or more of the group consisting of aromatic dicarboxylic acidshaving 8 to 20 carbon atoms and aliphatic diamines having 4 to 20 carbonatoms; and about 5 to about 50 mole percent aliphatic repeat unitsderived from monomers selected from one or more of the group consistingof an aliphatic dicarboxylic acid having 6 to 20 carbon atoms and saidaliphatic diamine having 4 to 20 carbon atoms; and a lactam and/oraminocarboxylic acid having 4 to 20 carbon atoms; Group (V) polyamideshaving a melting peak temperature of at least about 260° C., comprisinggreater than 95 mole percent semi-aromatic repeat units derived frommonomers selected from one or more of the group consisting of aromaticdicarboxylic acids having 8 to 20 carbon atoms and aliphatic diamineshaving 4 to 20 carbon atoms; and less than 5 mole percent aliphaticrepeat units derived from monomers selected from one or more of thegroup consisting of an aliphatic dicarboxylic acid having 6 to 20 carbonatoms and said aliphatic diamine having 4 to 20 carbon atoms; and alactam and/or aminocarboxylic acid having 4 to 20 carbon atoms. Thepolyamide may also be a blend of two or more polyamides.

Preferred polyamides include nylon 6, 6/6, and Group IV polyamideshaving a melting peak temperature less than about 270° C. and an amineend group concentration of 60 meq or less. These polyamides have amelting peak temperature sufficiently high so as not to limit the scopeof applications for the curable polyamide-filled acrylate copolymers,but not so high that production of the blends causes significantdegradation of the acrylate copolymer. Also preferred are polyamidesformed by ring opening or condensation of aminocarboxylic acids.

Polyamides suitable for use in the invention are widely commerciallyavailable, for example Zytel® resins, available from E. I. du Pont deNemours and Company, Wilmington, Del., USA, Durethan® resins, availablefrom Lanxess, Germany, and Ultramid® resins available from BASF, USA.

Preferably, the polyamide component of the filled acrylate copolymercompositions is present in the acrylate copolymer in the form ofapproximately spherical particles. The size of the particles isrelatively unimportant, though tensile strength of the cured compositionbecomes optimal when most of the particles are about 1 micrometer indiameter or smaller. Such compositions can be mixed, molded and/orextruded using conventional techniques to produce curable compositionsthat may be crosslinked with conventional curative systems to form awide variety of elastomer articles.

The polymer blend composition that is a component of the curablepolyamide-filled acrylate copolymer compositions of the inventioncomprises 40-90 weight percent of the amorphous acrylate copolymercomponent described herein and 10-60 weight percent of the polyamidecomponent described herein, based on the total weight of the acrylatecopolymer and polyamide components. The amorphous acrylate copolymercomponent may be made up of one or more than one acrylate copolymer ofthe type described herein as being suitable for use in the practice ofthe invention. Similarly, the polyamide component may be made up of oneor more than one polyamide of the type described herein as beingsuitable for use in the practice of the invention. Preferably, thecurable compositions will comprise 50 to 80 weight percent acrylatecopolymer component and 20 to 50 weight percent polyamide component,based on the total weight of the acrylate copolymer and polyamidecomponents. More preferably, the curable compositions will comprise 55to 70 weight percent acrylate copolymer component and 30 to 45 weightpercent polyamide component based on the total weight of the acrylatecopolymer and polyamide components. These ratios provide apolyamide-filled acrylate copolymer composition such that a curedarticle made therefrom exhibits sufficient Shore A hardness so thatlittle or no reinforcing filler is needed to further increase thehardness of the cured composition. In addition, the polymer blendsexhibit green strengths of less than about 2 MPa, as determined inaccordance with ASTM D6746-10 and have good cure responses whencompounded with a curative to form a curable composition, preferably atleast 2.5 dN-m and more preferably at least 4 dN-m, as determined inaccordance with ASTM D5289-07a using an MDR 2000 from Alpha Technologiesoperating at 0.5° arc and at test conditions of 177° C. for 24 minutes,where ML refers to the minimum torque value measured and MH refers tothe maximum torque value attained after the measurement of ML.

The polymer blend component of the curable polyamide-filled acrylatecopolymer compositions may be formed by mixing the polyamide componentinto the acrylate copolymer component at temperatures above the meltingpeak temperature of the polyamide, under conditions that do not producea dynamic cure of the acrylate copolymer, followed by cooling thethus-produced polymer blend to form a polyamide-filled acrylatecopolymer composition. That is, an amine curative will not be presentwhen the polyamide component and acrylate copolymer component are beingmixed. This is because the mixing temperature specified is above that atwhich crosslinking and/or gelling of the acrylate copolymer will occur.

Cooling of the composition formed by mixing the acrylate copolymercomponent and polyamide component serves to crystallize the polyamidedomains so that the polyamide becomes solid and therefore cannotcoalesce to form a continuous phase upon subsequent mixing, e.g., whenmixed with an amine curative to form a curable composition. Thetemperature below which the blend must be cooled can be determined bymeasuring the crystallization peak temperature according to ASTMD3418-08. The polyamide-filled acrylate copolymer compositions mayexhibit multiple crystallization peak temperatures. In such cases, thelowest crystallization peak temperature is taken as the temperaturebelow which the blend must be cooled to fully solidify the polyamidecomponent. Generally, the blend will be cooled to 40° C. or less, whichis sufficient to solidify the polyamides useful in the practice of thepresent invention.

The curable acrylate copolymer compositions described herein alsocomprise an amine curative. Preferably the amine curative is a diaminecurative or certain other nitrogen-containing curatives, such as diaminecarbamates that generate diamines. The curative will typically bepresent in an amount of from 0.1 to 10 parts per hundred parts ofacrylate copolymer, preferably 0.3-2 parts, more preferably 0.4-1 part.

Examples of suitable aromatic amines include4,4′-bis(4-aminophenoxy)biphenyl, 4,4′-diaminodiphenyl sulfide,1,3-bis(4-aminophenoxy)-2,2-dimethylpropane, 4,4′-diaminophenyl sulfone,2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 4,4′-oxydianiline,4,4′-methylenedianiline, 4,4′-diaminobenzanilide,1,3-bis(4-aminophenoxy)benzene,2,2-bis[4-(4-aminophenoxy)phenyl]propane, and phenylene diamine.Examples of suitable aliphatic amine and other curatives includehexamethylenediamine, hexamethylenediamine carbamate,N,N′-cinnamylidene-1,6-hexanediamine, ethylenediamine, diethylenetriamine, cyclohexane diamine, propylenediamine and butylenediamine.

In the curable acrylate copolymer composition, the preferable molarratio of primary amine groups in the polyamine curative to carboxylicacid or carboxylic anhydride or epoxy cure site monomer residues in thepolymer is in the range of 0.2 to 2.0, more preferably in the range of0.5 to 1.5, and most preferably in the range of 0.75 to 1.0.

The addition of curative to the polyimide-reinforced acrylate copolymercomposition will desirably take place at a temperature below thedecomposition temperature of the curative and below the temperature atwhich the crosslinking reaction occurs with the carboxyl, anhydride orepoxy groups of the acrylate copolymer. Generally, the addition willtake place at a temperature below 140° C., preferably at a temperatureno greater than 120° C. The addition of the curative may take placesimultaneously with the addition of optional processing ingredients,such as colorants, conventional carbon black or mineral reinforcingagents, antioxidants, processing aids, fillers and plasticizers, or itmay be an operation separate from addition of other ingredients. Theaddition may be conducted on a two-roll rubber mill or by using internalmixers suitable for compounding gum rubber compositions, includingBanbury® internal mixers, Haake Rheocord® mixers, Brabender Plastograph®mixers, Farrel Continuous Mixers, or single and twin screw extruders.

Accelerators are examples of additives that are useful in certainembodiments. That is, the rate of the amine cure may be increased by thepresence of basic vulcanization accelerators as generally known in theart. The accelerator may be a guanidine, an arylguanidine, analkylguanidine, an amidine, mixtures and salts thereof, or othermaterials as disclosed in U.S. Pat. No. 3,883,472. Representativeaccelerators include tetramethylguanidine, tetraethylguanidine,diphenylguanidine, di-orthotolyl guanidine and1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). The concentration of guanidineor amidine type accelerators is generally in the range of 0.5 to 5 phrof acrylate copolymer, preferably 1 to 3 phr. Preferred accelerators areDBU and DBU salts of organic acids due to their low toxicity and goodcure acceleration.

For example, a typical curing process might utilize 1.0 phr ofhexamethylenediamine carbamate and 1 phr of DBU salt based on 100 partsof acrylate copolymer elastomer, along with other ingredients. Afterblending on a roll mill, a curing step of 10 minutes at 175° C. at apressure of at least 10 MPa may be executed.

To achieve optimal heat aging resistance, an antioxidant is desirablyadded to the curable acrylate copolymer composition prior to curing.Useful antioxidants include, but are not limited to, aryl amines,phenolics, imidazoles, and phosphites. Thus, in some embodiments, theantioxidant will be a phosphorus ester antioxidant, a hindered phenolicantioxidant, an amine antioxidant, or a mixture of two or more of thesecompounds. The proportion of the antioxidant compound in the compositionis typically 0.1 to 5 phr, preferably about 0.5 to 2.5 phr. The weightratio of the phenolic or amine antioxidant to the phosphorus compound inthe mixtures is about 0.5 to 3, and preferably the ratio is about 1.

Examples of aryl amines that may be useful antioxidants include4,4′-bis(α,α-dimethylbenzyl)diphenylamine, diphenylamine and alkylateddiphenylamines, 4-aminodiphenyl amine (which also acts as a scorchretarder), and N-phenyl-N′-(p-toluenesulfonyl)-p-phenylenediamine.Examples of phenolic antioxidants include4,4′-butylenebis(6-t-butyl-m-cresol),1,3,5-trimethyl-2,4,6-tris-(3,5-di-t-butyl-4-hydroxybenzyl)benzene, and4,4′-thiobis-(3-methyl-6-t-butylphenol). Examples of phosphiteanti-oxidants include triphenylphosphite, bis(2,4-di-t-butylphenyl)pentraerythritol diphosphite, and tris(2,4-ditert-butylphenyl)phosphite.Examples of imidazole antioxidants include2-mercaptomethylbenzimidazole, and 2-mercaptobenzimidazole. Combinationsof antioxidants may be used, generally at levels between 0.5 and 5 phrbased on 100 parts of the acrylate copolymer rubber in the compound.

Suitable hindered phenolic antioxidants can be, for example 4,4′-butylidenebis(6-t-butyl-m-cresol),1,3,5-trimethyl-2,4,6-tris-(3,5-di-t butyl-4-hydroxybenzyl)benzene,2,6-di-t-butyl-α-dimethylamino-p-cresol and4,4′-thiobis-(3-methyl-6-t-butylphenol).

Preferred antioxidant compositions contain tri(mixed mono- anddinonylphenyl) phosphate mixed with either4,4′-butylidenebis(6-t-butyl-m cresol) or4,4′-bis(α,α-dimethylbenzyl)diphenylamine. Preferred antioxidantcompositions contain 4,4′-bis(α,α-dimethylbenzyl)diphenylamine(available commercially as Naugard® 445 from Chemtura Corp.).Particularly preferred antioxidant compositions include4-aminodiphenylamine, at levels up to about 2 phr (parts per hundredparts rubber) based on the acrylate copolymer (i.e. the acrylate rubber)component. Antioxidants may be added while the acrylate rubber is meltmixed with the polyamide, or after the blend has cooled.

The compositions of the invention may also comprise additional polymersprovided that when addition of such polymers occurs at a temperatureabove the melting peak temperature of the polyamide the presence of suchpolymers does not increase the green strength of the resultingpolyamide-filled acrylate composition to above about 2 MPa. For example,the polyamide-filled acrylate copolymer compositions of the inventionmay be blended with an acrylate copolymer to dilute the polyamidecontent of the inventive composition by any mixing process, either aboveor below the melting peak temperature of the polyamide. The acrylatecopolymer used for the blending process may be the same as or differentfrom that of the inventive composition, and may further comprisefillers, curatives, or other ingredients. Preferably, such dilutionoccurs at a temperature below that of the melting peak temperature ofthe polyamide, and if a curative is present, below the temperatureneeded to initiate curing.

In addition, the curable acrylate copolymer compositions may optionallycomprise additional components including plasticizers, process aids,waxes, pigments, and colorants. Such optional components will generallybe present in amounts of from about 0.1 phr to about 30 phr, based onthe weight of the acrylate rubber. The addition of such optionalcomponents may take place during preparation of the polyamide/acrylatecopolymer blend or at the time of mixing of curative and copolymerblend.

In general, compositions that result from mixing acrylate copolymerrubbers and polyamides may comprise a wide range of blend morphologies,ranging from those wherein discrete, discontinuous polyamide particlesexist within a continuous amorphous acrylate copolymer matrix, tocompositions wherein high aspect ratio polyamide “threads” are present,to compositions that comprise co-continuous structures, to compositionscomprising discrete acrylate copolymer domains within a continuous phaseof polyamide. Most of these compositions have morphologies that areunsuitable for use in the present invention, because the blends havevery high Mooney viscosities, i.e. Mooney viscosity ML 1+4, 100° C. ofgreater than about 120, and/or poor elastic properties such as a lowtensile elongation to break, and high compression set. However, if theratio of components is chosen as described herein, polyamide-filledacrylate copolymer compositions can be produced that have Mooneyviscosities below about 120 mL 1+4, 100° C. and good elastic properties.Such polyamide-filled acrylate copolymer compositions of the inventionand those suitable for use in the processes of the invention arecharacterized by having green strengths of less than about 2 MPa, asdetermined by measurement in accordance with ASTM D6746-10. Theresultant compositions have good processability and elastic properties.A green strength value less than about 2 MPa is a basic characteristicof the compositions of the invention and is confirmatory of the presenceof a continuous acrylate copolymer phase and a discontinuous polyamidephase in the polyamide-filled acrylate copolymer compositions. By“discontinuous polyamide phase” is meant that the polyamide is presentin the polymer blend compositions of the invention as dispersedparticles, or domains surrounded by a continuous amorphous acrylatecopolymer matrix. In general, the polyamide domains will be completelyisolated from each other within the continuous amorphous acrylatecopolymer matrix. However, in certain instances a small percentage, lessthan about 5%, of localized sites in the polymer blend composition mayexist wherein the polyamide domains are aggregated or connected to eachother. Such polymer blend compositions that have green strengths of lessthan about 2 MPa are considered to comprise a discontinuous polyamidephase for purposes of the invention. Preferably, the green strength ofthe polyamide-filled acrylate copolymers will be below about 1 MPA.

A green strength greater than 2 MPa indicates the blend has high Mooneyviscosity, poor extrusion processability, or poor elastic propertiesafter curing. These deficiencies may arise because the polyamide phaseof the blend is continuous or co-continuous with the acrylate copolymer,or because the end groups of the polyamide have reacted with the curesite of the acrylate copolymer to an extent that the acrylate polymerhas gelled, or any combination of the two.

In another embodiment, the invention is directed to a process forproduction of an acrylate copolymer composition to which an aminecurative may subsequently be added to provide a curable polyamide-filledacrylate copolymer composition. The process comprises a first step ofproviding a polymer blend composition comprising 40 to 90 wt. % of anamorphous acrylate copolymer as described herein and 10-60 wt. % of apolyamide having a melting peak temperature at least about 160° C. asdetermined in accordance with ASTM D3418-08 wherein the weightpercentages of the amorphous acrylate copolymer and polyamide are basedon the total weight of amorphous acrylate copolymer and polyamide. In asecond step the polymer blend composition is mixed at a temperatureabove the melting peak temperature of the polyamide thereby forming apolyamide-filled acrylate copolymer composition. After being cooled to atemperature less than the crystallization peak temperature of thepolyamide, the resultant polyamide-filled acrylate copolymer compositioncomprises a continuous acrylate copolymer phase and a discontinuouspolyamide phase and has a green strength of less than about 2 MPa asdetermined according to ASTM D6746-10. Cooling will generally preferablybe to a temperature of less than 40° C. Addition of an amine curative tothe composition at a mixing temperature below about 140° C. provides acurable composition.

Curing or crosslinking (also referred to as vulcanization) of thecurable polyamide-filled acrylate copolymer compositions of theinvention, typically involves exposing the curable composition,containing any optional ingredients (i.e. a curable compound) toelevated temperature and elevated pressure for a time sufficient tocrosslink the acrylate copolymer. Such operations generally areconducted by placing the curable polyamide-filled acrylate copolymercomposition into a mold that is heated in a press (often referred to aspress-curing). Alternatively, the curable compositions may be extrudedinto various shapes. Such extruded shapes or parts are often cured in apressurized autoclave. After the press cure or autoclave cycle iscompleted, this initial cure may be followed by an optional post-cureheating cycle at ambient pressure to further cure the acrylatecopolymer. For example, the vulcanizate may be formed and cured usingconventional press cure procedures at about 160° C. to about 200° C. forabout 2 to 60 minutes. Post-cure heating may be conducted at about 160°C. to about 200° C. for one to several hours. Once crosslinked, thecompositions described herein are not thermoplastic, but thermoset.Suitable cure conditions will depend on the particular curable compoundformulation and are known to those of skill in the art.

A further embodiment of the invention relates to curable acrylatecopolymers that include conventional reinforcing fillers in addition topolyamide filler. Such reinforcing fillers are known to those skilled inthe art, and include carbon black, amorphous precipitated and fumedsilica, crystalline silica such as diatomaceous earth clays such as,kaolin, bentonite, laponite, and montmorillonite, silicate minerals suchas magnesium silicate, titanium dioxide, wollastonite, antimony oxide,hydrated alumina, calcium carbonate, barium sulfate, and mixtures ofthese fillers. The fillers optionally may be modified using organiccompounds by known methods to improve either the dispersion in theacrylate copolymer or the adhesion to the acrylate copolymer. Suchmethods include treating the filler with organo-silanes or quaternaryammonium compounds. Conventional reinforcing fillers are most preferablyadded after production of the polyamide-filled acrylate copolymercomposition, at a mixing temperature less than the melting peaktemperature of the polyamide. This process ensures that the fillerresides in the acrylate copolymer phase.

As has been described herein, it is a basic characteristic of thepolyamide-filled compositions of the present invention that they haveenhanced heat resistance compared to similar compositions wherein onlyreinforcing fillers are present. Although the presence of reinforcingfillers is generally detrimental to heat resistance, it has been foundthat in certain instances cured acrylate copolymers having good heatresistance can be formed when particular blends of polyamide filler andone or more reinforcing fillers is present. Such reinforced compositionsconsist essentially of a) a polymer blend composition comprising i) 40to 90 wt. % of an amorphous acrylate copolymer as described herein andii) 10-60 wt. % of a polyamide having a melting peak temperature atleast 160° C., the weight percentages being based on the total weight ofacrylate copolymer and polyamide, b) an amine curative, and c) areinforcing filler. The amount of reinforcing filler present is anamount which does not result in an excessive increase in Shore Ahardness of the cured polyamide-filled acrylate copolymer composition.The appropriate amount of reinforcing filler may be easily determined bythe following method. Two curable acrylate copolymer compounds areprepared, differing only in presence of reinforcing filler. One compoundcomprises no reinforcing filler, while the other comprises a quantity ofreinforcing filler or fillers. The two compounds are cured by exposureto a temperature of 175° C. for 10 minutes in a closed mold at apressure of at least 10 MPa to form test specimens of thickness 1 to 2.5mm, followed by exposure of the unmolded, cured compositions to atemperature of 175° C. for 4 hours in a hot air oven. Shore A hardnessof the molded and post cured samples is determined at a test temperatureof 21° to 25° C. according to ASTM D 2240-06 (1 second reading).Subtracting the Shore A hardness of the unfilled sample from that of thefilled sample reveals the Shore A hardness increase attributable to thefiller content of the filled sample. Curable compounds comprisingpolyamide filled acrylate copolymers wherein any non-polyamidereinforcing filler content present results in an increase in the Shore Ahardness of no more than about 20 points as determined by the previouslydescribed method will have the heat resistance that is characteristic ofthe compositions of the invention.

The vulcanizates prepared from the polyamide-filled acrylate copolymercompositions described herein exhibit unusually good resistance toembrittlement during heat aging, as evidenced by a reduction in theamount of decrease in tensile elongation at break following heat agingat 190° C. for two to three weeks and a reduction in the increase inShore A hardness as a result of heat aging. Furthermore, theseadvantages are gained with no sacrifice in compression set resistance.In most cases, the present invention provides cured compositions havingimproved compression set resistance when curative levels similar tothose used in a conventional compound are utilized. For example,acrylate copolymer elastomers comprising very low levels ofcopolymerized ethylene units (2 weight % or less) tend to hardenseverely during hot air aging in the presence of carbon black. Replacingthe carbon black with a polyamide as a reinforcing filler can reduce theShore A increase after hot air aging for one week at 190° C. by over50%. Polyacrylates comprising high levels of ethylene (30 to 50% byweight), on the other hand, tend to lose elongation at break during hotair aging. In these cases, replacement of carbon black with a polyamidefiller can decrease the percentage loss of elongation during a 3 weekaging test at 190° C. by over 50%. This degree of improvement isunusual.

Vulcanizates of the polyamide-filled acrylate copolymer compositionsprepared by the processes described herein can be used in a wide varietyof industrial applications, for production of articles including wireand cable jacketing, spark plug boots, hoses, belts, miscellaneousmolded boots, seals and gaskets. Hose applications include turbo chargerhoses, transmission oil cooler hoses, power steering hoses, airconditioning hoses, air ducts, fuel line covers, and vent hoses.

Examples of seals include engine head cover gaskets, oil pan gaskets,oil seals, lip seal packings, O-rings, transmission seal gaskets, sealgaskets for a crankshaft or a camshaft, valve stem seals, power steeringseals, and belt cover seals.

Automotive tubing applications include axle vent tubing, PCV tubing andother emission control parts. The vulcanizates are also useful formanufacture of crankshaft torsional dampers where high damping over abroad temperature range is needed under high compressive and shearstrains. The vulcanizates also can be used to prepare noise managementparts such as grommets.

The invention is further illustrated by the following examples whereinall parts are by weight unless otherwise indicated.

EXAMPLES Materials Acrylate Copolymers

-   A1 Copolymer of methyl acrylate, ethylene and monoethyl maleate    comprising 55 wt. % (about 29 mole %) copolymerized methyl acrylate    units, and approximately 2 wt. % (about 0.6 mol %) copolymerized    units of monoethyl maleate; Mooney viscosity (ML 1+4) at 100° C. of    33.-   A2 Copolymer of methyl acrylate, ethylene, and monoethyl maleate    comprising 55 wt. % (about 30 mole %) copolymerized units of methyl    acrylate, and approximately 4 wt. % (about 1.3 mol %) copolymerized    units of monoethyl maleate; Mooney viscosity (ML 1+4) at 100° C. of    17.-   A3 Copolymer of ethyl acrylate, butyl acrylate and a carboxylic    acid-containing cure site monomer comprising about 74 wt. %    copolymerized units of ethyl acrylate, 24 wt. % copolymerized butyl    acrylate units and approximately 1.5 wt. % (about 1 mol %)    copolymerized units of carboxylic acid-containing cure site monomer;    Mooney viscosity (ML 1+4) at 100° C. of 42. Available as Nipol®    AR-212HR from Zeon Chemicals LP.-   A4 Copolymer of ethyl acrylate, butyl acrylate, ethylene and a    carboxylic acid-containing cure site monomer comprising    approximately 67.8 wt. % copolymerized units of ethyl acrylate,    approximately 29.8 wt. % copolymerized units of butyl acrylate,    about 1.5 wt. % (about 5.5 mol %) copolymerized units of ethylene,    and approximately 0.9 wt. % (about 0.5 mol %) by weight    copolymerized units of a carboxylic acid-containing cure site    monomer, Mooney viscosity (ML 1+4) at 100° C. of 46. Available as    ER-A413 from Denki Kagaku Kogyo KK.-   A5 Copolymer of ethyl acrylate, butyl acrylate a chlorine-containing    cure site monomer, and a carboxyl-containing cure site monomer;    Mooney viscosity (ML 1+4) at 100° C. of 27. Available as HyTemp®    4052EP from Zeon Chemicals LP.-   A6 Copolymer of methyl acrylate, ethylene and glycidyl methacrylate    comprising 55 wt. % copolymerized units of methyl acrylate (about 30    mole %), and approximately 2 wt. % (about 0.6 mol %) copolymerized    units of glycidyl methacrylate, an epoxide-containing cure site    monomer; Mooney viscosity (ML 1+4) at 100° C. of 28.-   A7 Copolymer of methyl acrylate, ethylene and monoethyl maleate    comprising 66 wt. % copolymerized units of methyl acrylate (about 40    mol %), and approximately 2 wt. % (about 0.7 mol %) copolymerized    units of monoethyl maleate.-   A8 Copolymer of methyl acrylate, ethylene and monoethyl maleate    comprising 55 wt. % copolymerized units of methyl acrylate (about 30    mol %), and approximately 2.5 wt. % (about 0.8 mol %) copolymerized    units of monoethyl maleate.

Polyamides

-   P1 Polyamide 6, inherent viscosity of 0.867 dL/g, melting peak    temperature of 220° C., available from BASF as Ultramid® B24.-   P2 Polyamide 6, inherent viscosity of 0.978 dL/g, melting peak    temperature of 220° C., available from BASF as Ultramid® B27.-   P3 Polyamide 6, inherent viscosity of 1.450 dL/g, melting peak    temperature of 220° C., available from BASF as Ultramid® B40.-   P4 Polyamide copolymer comprising copolymerized units of    hexamethylene diamine, adipic acid, and terephthalic acid, melting    peak temperature of approximately 262° C., amine end group    concentration of about 74 meq/kg, and inherent viscosity of 0.892    dL/g.-   P5 Polyamide 6/6, having a melting peak temperature of approximately    260° C., amine end group concentration of about 50 meq/kg, and    inherent viscosity of 1.002 dL/g.-   P6 Polyamide 6/10, having a melting peak temperature of    approximately 225° C., amine end group concentration of about 63    meq/kg, and inherent viscosity of 1.167 dL/g.-   P7 Polyamide 6, inherent viscosity of 1.24 dL/g, and a melting peak    temperature of 220° C. Available from BASF as Ultramid® B33.-   P8 Amorphous polyamide with a glass transition midpoint of about    125° C.-   P9 Polyamide 6/6, having a melting peak temperature of approximately    260° C., amine end group concentration of about 29 meq/kg, and    inherent viscosity of 1.634 dL/g.

Comparative Polymers

-   CP1 Ethylene vinyl acetate copolymer comprising 40% by weight vinyl    acetate.-   CP2 Linear low density polyethylene available from Exxon-Mobil Corp.    as LL1001.59.-   CP3 Thermoplastic rubber vulcanizate comprising a dynamically    crosslinked acrylate elastomer dispersed in polybutylene    terephthalate thermoplastic, available from DuPont as ETPV 60A01L    NC010.-   CP4 Fluoroelastomer comprising 60% by weight vinylidene fluoride and    40% hexafluoropropylene, having a Mooney viscosity (ML1+10, 121° C.)    of 25.-   CP5 Polyvinylidene fluoride, available from Arkema Inc. as Kynar®    461 polyvinylidene fluoride resin.-   CP6 Polybutylene terephthalate, available from DuPont as Crastin®    6219 thermoplastic polyester resin.

Other Ingredients

Curative 1: Diak™ 1, hexamethylenediamine carbamate curative availablefrom DuPont Performance Polymers.Curative 2: Sodium stearate, available from Sigma-Aldrich.Curative 3: Magnesium oxide, available from HallStar Corp. as Maglite®D.Curative 4: tris(hydroxymethyl)aminomethane, available fromSigma-Aldrich.N550 Carbon black: available from Cabot Corp. as Sterling SO carbonblack.N990 Carbon black: available from Cancarb Corp. as Thermax® N990Silica: available from Evonik Corp. as Ultrasil® VN3Antioxidant (AO-1): Naugard® 445 antioxidant, available from ChemturaCorp.Antioxidant (AO-2): 4-aminodiphenylamine (CAS 101-54-2), available fromSigma-Aldrich, also functions as a scorch retarder.Antioxidant (AO-3): N-isopropyl-N′-phenyl-1,4-phenylenediamine (CAS101-72-4), available from Sigma-Aldrich.Process aid: Vanfre® VAM organic phosphate ester, available from RTVanderbilt.Scorch retarder: Stearylamine, available from Akzo Nobel as Armeen® 18D.Accelerator 1: Vulcofac® ACT-55, tertiary amine complex absorbed in anamount of 70 wt. % on a silica carrier, available from Safic-Alcan.Accelerator 2: 3-(3,4-Dichlorophenyl)-1,1-dimethylurea, available fromSigma-Aldrich.Accelerator 3: 1,8-diazabicyclo[5.4.0]undec-7-ene, available fromSigma-Aldrich.

Test Methods

Mooney viscosity: ASTM D1646, ML 1+4, 100° C.Cure response: Measured per ASTM D5289-07a using an MDR 2000 from AlphaTechnologies operating at 0.5° arc. Test conditions of 177° C. for 24minutes. ML refers to the minimum torque value measured during the test,while MH refers to the maximum torque value attained after ML. T50 andT90 refer to the time to 50% and 90% torque, respectively, of thedifference between MH and ML.Compression set: ISO 815-1:2008, 25% compression, using type B moldedbuttons prepared using press cure conditions of 175° C. for 10 minutesfollowed by a four hour post cure in a hot air oven at 175° C. Time andtemperature of the test conditions as specified. Data reported are themedian values of 3 specimens.Tensile properties: ASTM D412-06, die C. Samples cut from 1.5 to 2.5 mmthick test specimens press cured at 175° C. for 10 minutes and postcured 4 hours at 175° C. in a hot air oven. Data reported are the medianvalue of 3 specimens. Stress at elongations of 25%, 50%, 100%, and 200%are listed as M25, M50, M100, and M200, respectively. The ruptureproperties of tensile strength and elongation are indicated as Tb andEb, (tensile at break and elongation at break, respectively). Testtemperature is 23° C.±2° C.Shore A hardness: measured using 6 mm thick samples composed of 2 mmthick plies, aged for 24 hours at ambient conditions of 23° C. and 50%relative humidity, per ASTM D2240-05 test method, using a type 2operating stand. The median value of 5 readings is reported.Heat aging: Tensile specimens, prepared as described above are hung in ahot air oven for the specified time and temperature. The specimens areconditioned at ambient conditions of 23° C. and 50% RH for at least 24hours before tensile properties are measured.Green strength: Measured in accordance with ASTM D6746-10 on the uncuredblend of acrylate copolymer and polyamide, prior to the addition of anyother ingredients. The blend is sheeted on a roll mill to about 2.5 mmthickness, then molded in a cavity having dimensions of 2 mm×76.2mm×152.4 mm. Molding conditions are 100° C. for 5 minutes under 30 tonsof pressure. Following removal from the press, the molded plaque iscooled for 30 minutes at room temperature between metal sheets. ASTMD412 Die C tensile specimens are then cut from the molded plaque in adirection parallel to the grain of the milled sheet. Median yield stressis reported. Test temperature is 23° C.±2° C.Inherent viscosity of polyamides: Measured in accordance with ASTMD2857-95, using 96% by weight sulfuric acid as a solvent at a testtemperature of 25° C. Samples were dried for 12 hours in a vacuum ovenat 80° C. prior to testing.Crystallization peak temperature: Measured in accordance with ASTMD3418-08.

Example 1

A series of polyamide-filled acrylate copolymers, B1-B11, was preparedby mixing an acrylate copolymer (A1 or A8) with a polyamide (P1, P2 orP3) in the ratios shown in Table 1. The polyamide-filled acrylatecopolymer blends were prepared using either Blend Method M or BlendMethod E, as indicated in the table.

Blend Method M consisted of the following steps: Polymers and any otheringredients were charged to a Haake Rheocord mixing bowl equipped withroller blades, operated at a set temperature of 20° C. greater than themelting peak temperature of the polyamide and at about 30 rpm rotorspeed. Once the mixing bowl was fully charged, the rotor speed wasincreased to 100 rpm. Polymer blend melt temperature was monitored, andwhen the polymer blend temperature reached the melting peak temperatureof the polyamide component, a timer was started. At the same time, thesetpoint for the bowl temperature was lowered to match the melting peaktemperature of the polyamide, and air cooling of the bowl was initiated.After three minutes of mixing, the rotors were stopped, at which pointthe temperature of the polymer blend was in the range of 20° C. to 35°C. greater than the melting peak temperature of the polyamide. Thepolyamide-filled acrylate copolymer blend was then removed from the bowland cooled to room temperature (about 25° C.) before further processing.

Blend Method E consisted of the following steps: Polyamide was meteredby weight loss feeder into the first barrel section of a 43 mm Berstorffco-rotating twin screw extruder with twelve barrel sections, operatingat a screw speed of 250 rpm. At the same time, acrylate copolymer wasmetered into the fourth section of the extruder via a speciallyconfigured extruder and a melt pump for accurate feed rates. Melttemperature of the polyamide/acrylate copolymer blend reached about 280°C. After exiting the twelfth barrel section, the resultantpolyamide-filled acrylate copolymer was pelletized and cooled to 25° C.before further processing.

Green strengths of the polyamide-filled acrylate copolymer compositionsare reported in Table 1.

Curable polyamide-filled acrylate copolymer compositions were preparedby compounding the polyamide-filled acrylate copolymer compositions andadditional ingredients on a roll mill. The compound formulations ofpolyamide-filled acrylate copolymer compositions B1-B11 are shown inTable 2. The resultant curable compositions were cured as described inthe test method section above (tensile properties) and tensile strength,elongation at break and modulus were determined according to theabove-described ASTM methods. Cure response and compression set werealso determined. The data reported for the cured compositions illustratethe improvement in physical properties of the cured polyamide-filledacrylate copolymer elastomer that is obtained when the green strength ofthe uncured polyamide-filled acrylate copolymer composition is less thanabout 2 MPa and the level of polyamide filler is between 10-60 wt. %,based on the combined weight of the polyamide and acrylate copolymer.Each of the comparative example curable compositions CE1-CE6 is eitherbased on a polyamide-filled acrylate copolymer blend composition thathas a green strength greater than 2 MPa or is based on apolyamide-filled acrylate copolymer blend that contains polyamide at alevel outside the range of 10-60 wt. %, based on the combined weight ofthe polyamide and acrylate copolymer.

TABLE 1 Composition B1 B2 B3 B4 B5 B6 B7¹ B8 B9 B10 B11 Polymer % % % %% % % % % % % A1 95 80 60 95 80 60 40 40 35 A8 60 45 P1 5 20 40 P2 40 55P3 5 20 40 60 60 65 Blend method M M M M M M M E E E E Green strength(MPa) 0.2 0.3 2.5 0.1 0.3 0.5 2.4 1.9 4.2 3.8 6.6 Crystallization peak168 84 173 77 81 88 85 nm nm 94 92 temperature (° C.) ¹The blendingmethod may affect the morphology of the polyamide-filled ethylenecopolymer compositions. Consequently, the green strength ofcompositionally identical polyamide-filled acrylate copolymercompositions can differ, as illustrated by blends B7 and B8. ²nm—notmeasured

TABLE 2 Composition¹ CE1 E1 CE2 CE3 E2 E3 CE4² E4 CE5 CE6 B1 105.26 B2125 B3 166.67 B4 105.26 B5 125 B6 166.67 B7 250 B8 250 B9 166.67 B10222.2 Curative 1 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 Accelerator 1 11 1 1 1 1 1 1 1 1 Scorch Retarder 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.50.5 Process Aid 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 1 1 AO-1 2 2 2 2 2 2 2 22 2 Cure response Ml (dN-m) 0.9 1.2 3.8 0.8 1.3 2.4 10.6 4.1 2.9 5.7 MH(dN-m) 4.2 6.3 16.2 4.3 5.5 10.6 24.3 25.9 19.9 32.6 MH − ML (dN-m) 3.35.1 12.4 3.5 4.2 8.2 13.7 21.8 17 26.9 Shore A hardness and tensileproperties after press cure and post cure Shore A Hardness 38 45 79 3745 63 80 82 85 89 M25 (MPa) 0.4 0.6 7.8 0.4 0.6 1.1 9.5 6.6 Tb (MPa) 3.19.4 16.3 3.3 8.3 17.7 26.2 29.1 19.7 28.1 Eb (%) 450 355 75 465 350 25590 120 19 23 Compression Set, 70 hrs/175° C. (%) 28 29 76 26 29 30 54 4693 92 ¹Curable polyamide-filled acrylate copolymer compositions, amountsof all ingredients are in parts per hundred of acrylate copolymer²Although CE4 and E4 are compositionally identical, tensile propertiesand compression set differ due to the morphology and green strengthdifferences of compositions B7 and B8.

Example 2

Two polyamide-filled acrylate copolymer compositions, B12 and B13, wereprepared by mixing an acrylate copolymer (A5 or A6) with polyamide P3 inthe ratios shown in Table 3 using Blend Method M. A5 is an acrylatecopolymer that is not curable by crosslinking with an amine curative. A6is an acrylate copolymer that is amine-curable.

TABLE 3 Composition B12 B13 % % A5 75 A6 75 P3 25 25 Blend method M MGreen strength (MPa) 0.1 0.2 Crystallization peak 150 154 temperature (°C.)

The polyamide-filled acrylate copolymer compositions of Table 3 werecooled after the acrylate copolymer was blended with polyamide. Theywere then compounded on a roll mill to form curable compositions CE8 andE5, as shown in Table 4. For comparison, two conventional carbon blackreinforced compounds that contain acrylate copolymers A5 and A6 (CE7 andCE9) were produced by mill mixing. The E5 and CE7-CE9 compositions werecured as described in the test method section above and tensilestrength, elongation at break and modulus were determined according tothe above-described ASTM methods. Cure response and compression set werealso determined. Physical properties were as shown in Table 4.

TABLE 4 Composition CE7 CE8 CE9 E5 phr phr phr phr A5 100 B12 133.33 A6100 B13 133.33 Curative 2 4 4 Accelerator 2 4 4 Curative 1 1.1 1.1Accelerator 3 1 1 AO-1 2 2 2 2 Process aid 1 1 0.5 0.5 N550 carbon black55 30 Cure Response ML (dN-m) 1.2 1 0.3 0.1 MH (dN-m) 5.5 3 6.4 5.2 MH −ML 4.3 2 6.1 5.1 Tensile Properties and Shore A Hardness After PressCure and Post Cure Shore A 52 46 62 59 Tb (MPa) 10 4.1 13.9 7.5 Eb 350155 180 140 Compression Set, 70 Hours/150° C. (%) 51 68 57 57

Because the chlorine cure site in A5 decomposes at the temperaturerequired for melt mixing polyamide, CE8 has a cure response (MH-ML) ofonly 2 dN-m. The low cure response of CE8 leads to inferior Shore Ahardness, tensile strength, and compression set compared to conventionalcompound CE7, based on the same acrylate rubber but reinforced withcarbon black. The amine curable rubber (A6) provides similar cureresponse in both the polyamide blend of E5 and conventional compound CE9containing carbon black. E5 exhibits Shore A hardness and compressionset similar to CE9, and acceptable tensile strength.

Example 3

Blend method M, described in Example 1, was used to prepare three blendcompositions B14-B16 composed of acrylate copolymer A2 and polyamide P2wherein the polymer components A2 and P2 were present in the same ratioin each blend. The B14-B16 blend compositions differed only in thepresence or absence of curative and the type of curative used during theprocess of mixing with molten polyamide. Dynamic curing of the acrylatecopolymer component A2 occurred during the process of mixing A2 and P2with Curatives 3 and 4 to form compositions B14 and B15. Composition B14was prepared by mixing acrylate copolymer A2 and polyamide P2 in thepresence of magnesium oxide (Curative 3) thereby forming a compositioncomprising an ionically crosslinked acrylate copolymer (a magnesiumionomer) dispersed in a polyamide matrix. Composition B15 was preparedby mixing acrylate copolymer A2 and polyamide P2 in the presence ofCurative 4 thereby forming a composition comprising covalentlycrosslinked acrylate copolymer A2 dispersed in polyamide P2. CompositionB16 was prepared by mixing A2 and P2 in the absence of a curative. Thegreen strength of composition B16 after mixing and cooling was 0.3 MPawhile the green strengths of compositions B14 and B15 were 9.1 and 7.8MPa, respectively. B14 and B15 were not processable at temperaturesbelow 160° C. and crumbled during the Mooney viscosity determination.The B16 composition was further processed by mixing on a roll mill withthe ingredients shown in Table 6 to form an amine-curablepolyamide-filled acrylate copolymer composition. The composition, E6,was cured using the conditions described in the test method sectionabove. Cure response and physical properties were as shown in Table 6.

TABLE 5 Composition B14 B15 B16 phr Phr phr A2 100 100 100 P2 66.6766.67 66.67 AO-1 0.833 0.833 Curative 3 2 Curative 4 0.75 Green Strength(MPa) 9.1 7.8 0.3 Mooney Viscosity * * 38 * no data; samples crumbledduring test

TABLE 6 Composition E6 Phr B16 166.67 Curative 1 0.6 Accelerator 3 1Scorch retarder 0.5 Process aid 0.5 AO-1 2 Cure response ML (dN-m) 3.3MH (dN-m) 7.5 Shore A hardness and tensile properties after press cureand post cure Shore A 58 M25 (MPa) 0.9 M50 (MPa) 1.5 M100 (MPa) 3.7 M200(MPa) 11.2 Tb (MPa) 13.9 Eb (%) 240

Example 4

Composition B17, a polyamide-filled acrylate copolymer composed of 60wt. % acrylate copolymer A1 and 40 wt. % polyamide P3 (nylon 6), wasproduced by extrusion using a 25 mm Berstorff twin screw extruderoperated at a screw speed of 250 rpm, an extrusion rate of 26 lb./hr.and a melt temperature of 240° C. The extrudate was smooth and shiny andwas collected and cooled to about 25° C. Blend B17 was used to producecomposition E7 by roll mill mixing at approximately 50° C. batchtemperature with the ingredients shown in Table 7. The cure response,initial tensile properties and hot air aged properties of E7 are alsolisted in Table 7. Composition B18, a blend of 60% acrylate copolymer A1and 40% polyamide P6 was produced using the same equipment operated at ascrew speed of 150 rpm, an output rate of 20 lb./hr., and a melttemperature of 240° C. The extrudate was rough, nervy, and tough, andperformed as if the acrylate elastomer had partially crosslinked orgelled. Melt temperature was increased to 250° C. in an attempt toproduce a smooth extrudate, but there was no improvement. The feed rateof the polyamide P6 was then reduced in stages, and extrudate roughnesswas eliminated when the P6 level had dropped to 25% in the polymerblend.

TABLE 7 Composition E7 phr B17 166.67 Curative 1 0.6 Accelerator 1 1AO-2 0.91 Process aid 1 Cure response ML (dN-m) 0.7 MH (dN-m) 12.7 ShoreA and tensile properties after press cure and post cure Shore A 65 Tb(MPa) 19.3 Eb (%) 290 Shore A and tensile properties after 3 weeks at190° C. hot air aging Shore A 57 Tb (MPa) 10.3 Eb (%) 180

Example 5

Composition B19, a blend of 60 wt. % acrylate copolymer A8 and 40 wt. %polyamide P7 (nylon 6) was produced by extrusion using a 25 mm Berstorfftwin screw extruder operated at a screw speed of 150 rpm, an extrusionrate of 20 lb./hr. and a melt temperature of 250° C. The extrudate wassmooth and shiny, was collected and cooled to about 25° C. and was rollmill compounded with the ingredients shown in Table 8 to producecomposition E8. Composition E8 exhibited excellent cure response,initial properties, and hot air aged properties. Composition B20, ablend of 60 wt. % acrylate copolymer A8 and 40 wt. % polyamide P4 wasproduced using the same equipment operated at the same screw speed andextrusion rate, but at a melt temperature of 280° C. The extrudate wasrough, nervy, and tough, and performed as if the acrylate elastomer hadpartially crosslinked or gelled.

TABLE 8 Composition E8 phr B19 166.67 Curative 1 0.6 Accelerator 1 1AO-2 0.91 process aid 1 Cure response ML (dN-m) 0.89 MH (dN-m) 8.5 ShoreA and tensile properties after press cure and post cure Shore A 60 Tb(MPa) 18 Eb (%) 325 Shore A and tensile properties after 3 weeks at 190°C. hot air aging Shore A 53 Tb (MPa) 8.1 Eb (%) 165

Example 6

The compositions shown in Table 9, wherein all amounts are in weightpercent, were prepared using a Haake Rheocord® mixer. For each of thepolymer blends B21-B29, acrylate copolymer A1 and a second polymericcomponent (one of Comparative Polymers CP1-CP6 or acrylate copolymer A3)were added to the heated mixing bowl and processed for 3 minutes at 50rpm. The temperature of the polymer blend was maintained at a pointapproximately 20° C. higher than the melting peak temperature of thesecond polymer component if that polymer was a semi-crystallinethermoplastic resin or at 60° C. if the second polymer was an amorphouselastomer. Processing (mixing) temperatures are listed in Table 9. Priorto processing, polymers CP3, CP6, P2, and P4 were dried for 4 hours at120° C. in a vacuum oven. After processing, the blend compositions werecooled to room temperature (about 25° C.).

TABLE 9 Composition B21 B22 B23 B24 B25 B26 B27 B28 B29 % % % % % % % %% A1 75 75 75 75 75 75 75 75 75 CP1 25 CP2 25 CP3 25 CP4 25 CP5 25 A3 25CP6 25 P2 25 P4 25 Mixing Temp. (° C.) 80 140 240 60 200 60 240 240 280

Curable compositions CE10 through CE17, E9 and E10 were prepared fromblends B21-B29 by mixing the ingredients listed in Table 10 on a rollmill. Composition CE10 is an acrylate copolymer control compound thatdoes not contain a polyamide filler. Cure response, tensile properties,Shore A hardness, and compression set data are also shown in the table.

The cure response data indicate that the CE11 through CE16 compositionshave a weak cure response, such that in some cases the MH-ML differenceis less than 2.5 dN-m, and in all cases MH-ML is less than 4.0 dN-m. Allthe comparative examples except CE17 exhibit a smaller cure responsethan that of the acrylate copolymer control composition (CE10) that doesnot contain a second polymeric component.

After press cure and post cure according to the conditions described inthe test method section herein, compositions E9 and E10, which arecompositions of the invention, exhibit a combination of Shore Ahardness, heat aging resistance, and compression set unmatched by any ofthe comparative example compositions. In particular, the E9 and E10compositions exhibit values of Shore A hardness greater than 40,elongation at break after hot air aging for three weeks at 190° C. ofgreater than 100%, and a change in elongation at break of less than 50%from the unaged value.

TABLE 10 Composition CE10 CE11 CE12 CE13 CE14 CE15 CE16 CE17 E9 E10 phrphr phr phr phr phr phr phr phr phr A1 100 B21 133.3 B22 133.33 B23133.33 B24 133.33 B25 133.33 B26 133.33 B27 133.33 B28 133.33 B29 133.33Curative 1 1 1 1 1 1 1 1 1 1 1 Accelerator 1 1 1 1 1 1 1 1 1 1 1 Scorchretarder 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 AO-1 2 2 2 2 2 2 2 2 22 Process aid 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Cure Response ML(dN-m) 0.2 0.2 0.2 1.1 0.2 0.6 0.3 2.0 1.1 2.2 MH (dN-m) 4.8 2.9 3.0 3.61.0 3.6 3.9 8.2 8.6 7.6 MH − ML (dN-m) 4.6 2.7 2.8 2.5 0.8 3 3.6 6.2 7.55.4 Tensile Properties and Shore A Hardness After Press Cure and PostCure Shore A 36 39 55 35 nm¹ 51 30 50 49 49 M50 (MPa) 0.55 0.7 1.7 0.61.2 0.4 1 1 0.9 Tb (MPa) 2.4 5.5 7.3 3.9 9.2 1.6 9.5 6.9 11.2 Eb (%) 470570 500 360 390 415 315 230 260 Tensile Properties and Shore A HardnessAfter One Week at 190° C. Shore A 32 34 50 30 nm¹ 47 25 49 48 49 M50(MPa) 0.4 0.5 1 0.5 0.9 0.3 0.8 0.8 1 Tb (MPa) 1.7 2.5 1.5 2.4 7.9 1.48.9 7.3 9.4 Eb (%) 440 460 120 350 355 460 250 205 270 TensileProperties and Shore A Hardness After Two Weeks at 190° C. Shore A 24 3053 29 nm¹ 45 20 49 45 46 M50 (MPa) 0.3 0.5 0.4 1.0 0.2 1.0 0.7 0.7 Tb(MPa) 0.8 2.2 1.9 1.6 4.8 2.5 4.3 5.9 5 Eb (%) 230 125 5 215 185 290 150220 185 Tensile Properties and Shore A Hardness After Three Weeks at190° C. Shore A 30 43 57 33 nm¹ 50 25 50 45 45 M50 (MPa) 0.3 1 0.5 1.70.3 1.5 0.6 0.7 Tb (MPa) 1 1.5 2.4 1.5 6.6 1 4.3 3.9 3.8 Eb (%) 180 8015 140 130 145 105 180 150 Change in Shore A Hardness and Elongation atBreak After Three Weeks at 190° C. Shore A (points) −6 4 3 −2 −1 −6 1 −4−3 Eb (%) −62 −86 −97 −61 −67 −65 −67 −22 −42 Compression Set, 70Hours/150° C. (%) 19 22 13 32 nm¹ 41 19 24 14 19 ¹Not measured -Compound did not cure.

Example 7

Composition B30, a polyamide-filled acrylate copolymer compositioncomposed of 62.5 wt. % acrylate copolymer A1 and 37.5 wt. % polyamide P3(nylon 6) was produced by extrusion using a 25 mm Berstorff twin screwextruder operated at a screw speed of 200 rpm, an extrusion rate of 11.8kg/hour and a melt temperature of 260° C. The blend was cooled to 25° C.before further processing. Composition B31, a polyamide-filled acrylatecopolymer composition composed of 55 wt. % acrylate copolymer A1 and 45wt. % polyamide P3 (nylon 6) was produced by Blend Method E, describedin Example 1. Green strength of the polymer blend compositions B30 andB31 are reported in Table 11.

TABLE 11 Composition B30 B31 % % A1 62.5 55 P3 37.5 45 Green strength(MPa) 0.5 0.5 Crystallization peak nm 100 temperature (° C.)

Compositions B30 and B31 were mixed on a roll mill with the ingredientsand amounts shown in Table 12 to produce curable acrylate copolymercompositions E11, E12, and E13. Cure response and physical properties ofthe cured blends before and after aging are shown in Table 12. The heataging results shown in Table 12 indicate AO-2 is the most effective ofthe three antioxidants for the cured polyamide-filled acrylate copolymercompositions tested.

TABLE 12 Composition E11 E12 E13 phr phr phr B30 160 B31 181.82 181.82Curative 1 0.6 0.6 0.6 Accelerator 1 1 1 1 Scorch retarder 0.5 0.5 AO-12 AO-2 2 AO-3 2 Process aid 1 0.5 0.5 Cure response ML (dN-m) 0.55 0.81.9 MH (dN-m) 12.1 11.5 12.5 Tensile Properties and Shore A Hardnessafter Press Cure and Post Cure Shore A 65 67 67 Tb (MPa) 18.5 15.1 14.6Eb (%) 280 262 227 Tensile Properties and Shore A Hardness after 3 weeks190° C. heat aging Shore A 54 60 57 Tb (MPa) 5.2 8.7 4.6 Eb (%) 122 142101 Change in Shore A, Tb, and Eb after 3 weeks 190° C. heat aging ShoreA (points) −11 −7 −10 Tb (%) −72 −42 −68 Eb (%) −56 −46 −56

Example 8

Compositions B32 and B33 are polyamide-filled acrylate copolymercompositions composed of 60 wt. % acrylate copolymer A1 and 40 wt. %polyamide P8 or 40 wt. % of polyamide P3, respectively. B32 was producedusing Blend Method M described in Example 1, while B33 was produced byBlend Method E of Example 1. Polyamide P8 is an amorphous polyamidehaving a glass transition midpoint temperature of 125° C., whereaspolyamide P3 has a melting peak temperature above 160° C. B33 wasfurther characterized by a green strength of 0.4 MPa and acrystallization peak temperature of 95° C.

Curable acrylate copolymer compositions CE18 and E14 were prepared bymixing B32 with the ingredients listed in Table 13 using a roll mill.CE18 exhibits a poor cure response because the polyamide P8 is fluid atthe cure temperature, whereas E14 provides a high state of cure eventhough E14 contains less curative than CE18.

TABLE 13 Curable composition CE18 E14 phr Phr B32 166.67 B33 166.67Curative 1 0.6 0.45 Accelerator 1 1 1 Scorch retarder 0.5 0.5 Processaid 0.5 0.5 AO-1 2 2 Cure response ML (dN-m) 1.2 0.9 MH (dN-m) 3.1 7.9MH − ML 1.9 7

Example 9

A series of polyamide-filled acrylate copolymers, B34-B48, was preparedby mixing 60 parts of an acrylate copolymer (A1, A2 or A4) with 40 partsof a polyamide (P1, P2, P3, P5, or P7). Blend B3 from Table I isincluded in this series as well. The polyamide-filled acrylate copolymerblends were prepared using Blend Method M described in Example 1. Table14 lists the blend compositions prepared, along with the green strengthand Mooney viscosity of the blends. These results show that acrylatecopolymer A1 forms blends comprising 40% by weight polyamide having lowgreen strength and Mooney viscosity when the polyamide has an inherentviscosity greater than about 0.9 dL/g. Acrylate copolymer A2 formsblends comprising 40% by weight polyamide having low green strength andMooney viscosity using any of the polyamide types tested. Acrylatecopolymer A4 forms blends comprising 40% by weight polyamide having lowgreen strength and Mooney viscosity using only polyamides havinginherent viscosity greater than 1.3 dL/g.

Curable compositions and their properties based on certain blends ofTable 14 are shown in Table 15 (similar results for blend B3 can befound in Table 2, compound CE3). These results show thatpolyamide-filled acrylate co-polymers, within a given type of acrylateco-polymer, exhibit superior elastic properties such as Eb andcompression set resistance when the green strength of the blend is lessthan about 2 MPa.

TABLE 14 Composition B3 B34 B35 B36 B37 B38 B39 B40 B41 B42 B43 B44 B45B46 B47 B48 % % % % % % % % % % % % % % % % A1 60 60 60 60 60 A2 60 6060 60 60 60 A4 60 60 60 60 60 P1 40 40 P2 40 40 40 P7 40 40 40 P3 40 40P5 40 40 40 P9 40 40 40 Green strength (MPa) 2.5 0.5 0.5 0.8 0.5 0.4 0.30.3 0.3 0.4 0.3 2.9 2.9 1 3.6 1 Mooney Viscosity >220 71 71 76 69 40 4241 40 49 43 137 126 57 >220 58 (Mooney units)

TABLE 15 Composition E15 E16 E17 CE19 E18 E19 phr phr phr phr phr phrB37 166.67 B38 166.67 B43 166.67 B44 166.67 B46 166.67 B48 166.67curative 1 0.6 0.6 0.6 0.6 0.6 0.6 accelerator 1 1 1 1 1 1 1 scorchretarder 0.5 0.5 0.5 0.5 0.5 0.5 process aid 0.5 0.5 0.5 0.5 0.5 0.5AO-1 2 2 2 2 2 2 Cure response ML (dN-m) 1.8 0.9 1.4 2.9 1.5 1.9 MH(dN-m) 12.8 7.6 7.9 14.5 8.1 8 Shore A hardness and tensile propertiesafter press cure and post cure Shore A 65 65 62 80 64 67 M25 (MPa) 1.31.5 1 12.8 4.2 4.9 Tb (MPa) 15.4 9.2 11.7 20.5 12.9 12.6 Eb (%) 235 215230 50 90 80 Compression set, 70 hours at 175° C. (%) 30 40 59 83 56 63

Example 10

A polymer blend composition, B49 composed of 73.4 wt. % acrylatecopolymer A1 and 26.6 wt. % polyamide 4 was produced on a 25 mmBerstorff twin screw extruder that was operated at 150 rpm with a totalpolymer output of 11.8 kg/hr. Melt temperature of the blend was 282° C.The polymer blend composition was extruded onto a water cooled belt andcooled to room temperature (about 25° C.). Composition and physicalproperties of B49 are shown in Table 16.

TABLE 16 Composition B49 % A1 73.4 P4 26.6 Green strength (MPa) 0.4Mooney viscosity 52 Crystallization peak 112 temperature (° C.)

Curable acrylate copolymer compositions E20, E21, and E22, havingcompositions as shown in Table 17, were prepared on a roll mill usingB49 as the polymer blend component. A curable acrylate copolymercomposition CE20 was prepared in the same manner using acrylatecopolymer A1 and carbon black, a conventional reinforcing filler. Allthe compositions in Table 17 cure well and have good initial physicalproperties. E20, E21, and E22 retain tensile elongation at break greaterthan 100% after heat aging 3 weeks at 190° C., whereas CE20 exhibitstensile elongation at break of less than 100% after heat aging for onlytwo weeks at 190° C.

TABLE 17 Composition E20 E21 E22 CE20 phr phr phr phr B49 136.2 136.2136.2 A1 100 Curative 1 0.55 0.7 0.95 1.1 Accelerator 1 2 1 1 2 Scorchretarder 0.5 0.5 0.5 Process aid 0.5 0.5 0.5 0.5 AO-1 2 2 2 4 N550carbon black 45 Cure response ML (dN-m) 0.7 0.7 0.6 0.7 MH (n-m) 7.8 9.710.2 12.9 T′50 (min) 3.2 4.3 5.3 2.5 T′90 (min) 9.7 13.9 16.1 7.7Tensile properties and Shore A hardness after press cure and post cureShore A Hardness 54 54 54 66 M50 (MPa) 1.1 1.2 1.2 1.9 M100 (MPa) 2.02.2 2.4 4 M200 (MPa) 6.4 8.0 10.0 11.6 Tb (MPa) 16.4 17.3 19.7 24 Eb (%)320 300 270 400 Tensile properties and Shore A hardness after 2 weeksheat aging at 190° C. Shore A 47 50 50 75 M50 (MPa) 0.8 0.8 0.9 4.4 M100(MPa) 1.5 1.4 1.7 M200 (MPa) 5.4 5 7.6 Tb (MPa) 5.9 8.7 8.6 6.4 Eb (%)210 250 210 80 Change in Eb and Shore A Eb (%) −34 −17 −22 −80 Shore A(pts.) −7 −4 −4 9 Tensile properties and Shore A hardness after 3 weeksheat aging at 190° C. Shore A 45 47 48 Not M50 (MPa) 0.9 0.8 0.9 TestedM100 (MPa) 2.1 2 2.1 Tb (MPa) 3.7 2.6 3 Eb (%) 130 110 115 Compressionset, 25% compression, 70 hrs. at 150 C. (%) 20 14 14 20

Example 11

A series of curable polyamide filled acrylate copolymers was prepared byblending composition B8, a blend of 60 wt. % polyamide and 40 wt. %acrylate copolymer A1 described in Example 1, with sufficient gumacrylate rubber to lower the polyamide content in the polyamide-filledacrylate copolymer composition to 40 wt. %. This mixing process wasconveniently accomplished via mill mixing at a temperature less than160° C., i.e. less than the melting peak temperature of the polyamide.Curative and other ingredients were added while the dilution occurred.The curable compositions and their properties are shown in Table 18.Compositions E23, E24, and E25, exhibit good cure response, compressionset resistance and tensile properties both initially and after heataging for two weeks at 190° C.

TABLE 18 Composition E23 E24 E25 phr phr phr B8 111.11 111.11 111.11 A155.55 A3 55.55 A4 55.55 Curative 1 0.6 0.6 0.6 Accelerator 1 1 1 1Scorch retarder 0.5 0.5 0.5 Process aid 1 1 1 AO-1 2 2 2 Cure responseML (dN-m) 0.96 1.3 1.3 MH (dN-m) 11.3 10.5 10.3 Tensile properties andShore A hardness after press cure and post cure Shore A 63 61 60 Tb(MPa) 21.3 17.5 18.4 Eb (%) 270 170 195 Tensile Properties and Shore Ahardness after 2 Weeks at 190° C. hot air aging Shore A 55 52 52 M25(MPa) 0.74 0.71 0.68 M50 (MPa) 1.2 1.5 1.3 M100 (MPa) 3.3 6.3 5.3 Tb(MPa) 6.5 8.3 7.8 Eb (%) 135 116 125 Compression Set, 70 hours at 175°C. (%) 34 30 28

Example 12

Two polyamide-filled acrylate copolymer blend compositions, B50 and B51having compositions in weight percent as shown in Table 19 were preparedusing Blend Method M of Example 1.

TABLE 19 Composition B50 B51 % % A3 80 A4 80 P2 20 20 Green strength(MPa) 0.1 0.3 Crystallization peak 82 80 temperature (° C.)

Curable polyamide-filled acrylate copolymer compounds were produced byroll mill mixing B50 and B51 with the ingredients shown in Table 20.Compositions CE21 and CE22 comprise a high level (55 phr) of N550 carbonblack filler and no polyamide, compositions CE23 and CE24 comprise a lowlevel (15 phr) of N550 carbon black filler and no polyamide,compositions CE25 and CE26 are free of carbon black or polyamidefillers, and compositions E26 and E27 comprise polyamide and a low level(15 phr) of N550 carbon black filler. The contribution to Shore Ahardness attributable to 15 phr and 55 phr carbon black in the curedacrylate copolymer compositions can be computed by subtraction of theShore A hardness of the compounds free of carbon black from the Shore Ahardness of the corresponding compounds comprising solely carbon blackfiller. Using this method of computation indicates that the presence of55 phr N550 in the acrylate copolymer compositions increases Shore Ahardness by more than 40 points, whereas the presence of 15 phrincreases Shore A hardness by 10 to 11 points, depending on the acrylatecopolymer in the composition.

Because E26 and E27 rely on carbon black for only a minor amount ofreinforcement, they exhibit heat aging superior to that of CE21 and CE22as indicated by the lower percent change in elongation at break andShore A hardness after heat aging for 3 weeks at 190° C.

TABLE 20 Composition CE21 CE22 CE23 CE24 CE25 CE26 E26 E27 phr phr phrphr phr phr phr phr A3 100 100 100 A4 100 100 100 B50 125 B51 125Curative 1 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 Accelerator 1 1 1 1 1 1 1 1 1Scorch retarder 0.6 0.6 0.6 0.6 0.6 0.6 0.6 0.6 AO-1 2 2 2 2 2 2 2 2process aid 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 N550 carbon black 55 55 1515 15 15 Cure response ML (dN-m) 1.1 0.9 0.7 0.8 0.4 0.5 1.1 0.8 MH(dN-m) 8.3 7.9 3.7 3.7 2.4 2.5 5.8 5.3 Shore A hardness and tensileproperties after press cure and post cure Shore A (1 sec) 59 62 27 26 1715 42 47 M50 (MPa) 1.4 1.5 0.5 0.4 0.2 0.2 1.7 1.9 M100 (MPa) 3.1 3.30.9 0.7 0.4 0.3 4.7 5.13 M200 (MPa) 9 9.8 3.4 2.1 1 0.5 12.2 Tb (MPa)12.5 12.8 6.1 4.7 1.4 1.1 11.1 12.6 Eb (%) 280 270 275 295 250 280 190210 Shore A points 42 47 10 11 0 0 10 11 attributable to N550 carbonblack Heat Aged 3 weeks at 190° C. Shore A 85 75 Not Not not Not 46 47M50 (MPa) 6.3 5 Tested Tested tested Tested 1.3 1.2 M100 (MPa) 4 3 Tb(MPa) 7.1 6.4 4.6 6.2 Eb (%) 70 90 120 180 Change in Shore A hardnessafter 3 weeks at 190 C. Points 26 13 4 0 % Change in Eb after 3 weeks at190° C. % change −75 −67 −37 −14

Example 13

A series of curable polyamide-filled acrylate copolymers, E28-E30 andCE27, was prepared by compounding composition B31, prepared as describedin Example 7, with the ingredients shown in Table 21 on a rubber mill.Composition B31 comprises 45 weight % polyamide P3 and 55 wt. % acrylatecopolymer A1. A second series of curable acrylate copolymers, CE28-CE32was prepared in substantially the same manner except that carbon blackwas utilized as a filler in place of polyamide. As shown in Table 21,for curable copolymer compositions E28-E30 and CE27, the polyamidecontent of B31 is successively diluted with increasing amounts ofacrylate copolymer while the concentration of N550 carbon blackincreases to maintain an approximately constant Shore A hardness in thecured compositions. CE28-CE31 comprise only carbon black as areinforcing filler, while CE32 is an unreinforced compound that containsneither carbon black nor polyamide fillers. The Shore A hardness valuesof CE28-CE32 permit calculation of the Shore A hardness pointscontributed by the N550 carbon black, ranging from zero points for E28to 28 points for CE28.

After two and three weeks of hot air aging at 190° C., cured samples ofE28-E30, wherein carbon black contributes less than about 20 pointsShore A hardness, exhibit greater tensile strength and elongation thancured samples of CE27 and CE28, which derive more than 20 points Shore Ahardness from carbon black. Cured samples of E28-E30 also exhibit lesschange in Shore A hardness during heat aging than cured samples of CE27and CE28.

TABLE 21 Composition E28 E29 E30 CE27 CE28 CE29 CE30 CE31 CE32 phr phrphr phr phr phr phr phr phr B31 181.8 133.3 88.9 44.4 0 A1 26.7 51.175.6 100 100 100 100 100 Curative 1 1 1 1 1 1 1 1 1 1 Accelerator 1 1 11 1 1 1 1 1 1 AO-2 1 1 1 1 1 1 1 1 1 Process aid 0.5 0.5 0.5 0.5 0.5 0.50.5 0.5 0.5 N550 carbon black 0 15 25 35 45 15 25 35 Cure response ML(dN-m) 1.7 1.3 1.1 0.9 0.9 0.4 0.5 0.7 0.3 MH (dN-m) 18.4 17.4 15.6 14.212.2 7.3 8.9 10.2 5.4 Shore A hardness and tensile properties afterpress cure and post cure Shore A 68 67 67 65 65 47 53 60 37 Tb (MPa)23.5 22.1 22.6 23.7 23.7 18.1 22.6 23.6 2.3 Eb (%) 230 229 290 345 425520 510 475 450 Shore A points 0 10 16 23 28 10 16 23 0 attributable toN550 Shore A and tensile properties after 2 weeks hot air aging at 190°C. Shore A 65 65 68 70 80 Tb (MPa) 11.5 14.9 13.6 10.7 4.9 Eb (%) 150160 145 115 35 Shore A and tensile properties after 3 weeks hot airaging at 190° C. Shore A 62 65 68 77 88 Tb (MPa) 8.4 9.6 5.9 5 5.5 Eb(%) 120 105 70 45 5

Example 14

A series of curable polyamide-filled acrylate copolymers, E31-E33, wasprepared by compounding composition B31, prepared as described inExample 7, with the ingredients shown in Table 22 on a rubber mill.Composition B31 comprises 45 weight % polyamide P3 and 55 wt. % acrylatecopolymer A1. A second series of curable acrylate copolymers, CE33-CE36was prepared in substantially the same manner except that N990 carbonblack was utilized as a filler in place of polyamide. As shown in Table22, for curable copolymer compositions E31-E33 the polyamide content ofB31 is successively diluted with increasing amounts of acrylatecopolymer while the concentration of N990 carbon black increases tomaintain an approximately constant Shore A hardness in the curedcompositions. CE33-CE36 comprise only carbon black as a reinforcingfiller. CE32 (see Example 13) is used as the unreinforced referencecompound that contains neither carbon black nor polyamide fillers.

N990 carbon black is less reinforcing than N550, and therefore more N990is needed to increase the Shore A hardness of the cured compound.Compounds E31-E33 derive less than 20 points Shore A hardness from theN990 carbon black, and therefore exhibit better resistance to hot airaging at 190° C. for two to three weeks than CE33.

TABLE 22 Composition E31 E32 E33 CE33 CE34 CE35 CE36 phr phr Phr Phr phrphr phr B31 133.3 88.9 44.4 A1 26.7 51.1 75.6 100 100 100 100 Curative 11 1 1 1 1 1 1 Accelerator 1 1 1 1 1 1 1 1 AO-2 1 1 1 1 1 1 1 Process aid0.5 0.5 0.5 0.5 0.5 0.5 0.5 N990 carbon black 25 45 60 80 25 45 60 Cureresponse ML (dN-m) 1.5 1.05 0.78 0.65 0.36 0.45 0.51 MH (dN-m) 17.1 1614.1 12.5 7.3 9 10.8 Shore A hardness and tensile properties after presscure and post cure Shore A 67 65 61 61 44 49 54 Tb (MPa) 20.9 18 15.312.3 12.4 13.5 13.5 Eb (%) 250 290 335 385 485 470 475 Shore A points 712 17 24 7 12 17 attributable to N990 Shore A and tensile propertiesafter 2 weeks hot air aging at 190 C. Shore A 59 64 63 67 Tb (MPa) 13.412.2 11.5 4.1 Eb (%) 170 160 165 60 Shore A and tensile properties after3 weeks hot air aging at 190 C. Shore A 61 64 65 81 Tb (MPa) 8.7 8 5.34.1 Eb (%) 115 110 75 20

Example 15

Curable polyamide-filled acrylate copolymers, E34, E35, and CE40, wereprepared by mill mixing polyamide-filled polyacrylate copolymercomposition B31, prepared as described in Example 7, with varying levelsof silica filler and gum acrylate copolymer A1. Composition B31comprises 45 weight % polyamide P3 and 55 wt. % acrylate copolymer A1.Curable acrylate copolymer compounds CE37-CE39 were mill mixed in thesame manner except that silica was utilized as the only filler in thecompound, so that the increase in Shore A hardness attributable to thesilica filler can be determined. The ingredients in the curablecompositions are shown in Table 23. Curable copolymer compositionsE34-E35 and CE40 contain increasing levels of silica filler, such thatthe silica contributes 8, 15, and 23 points Shore A hardnessrespectively to the cured compound. CE32 (see Example 13) was used asthe unreinforced reference compound that contains neither polyamide norsilica. Compounds E34 and E35 derive less than 20 points Shore Ahardness from silica, and therefore exhibit better resistance to hot airaging for two to three week at 190° C. than CE40.

TABLE 23 Composition CE37 CE38 CE39 E34 E35 CE40 phr phr phr phr phr phrB31 88.9 74.1 88.9 A1 100 100 100 51.1 59.2 51.1 Curative 1 1 1 1 1 1 1Accelerator 1 1 1 1 1 1 1 AO-2 1 1 1 1 1 1 Process aid 0.5 0.5 0.5 0.50.5 0.5 Silica 12 24 36 12 24 36 Cure response ML (dN-m) 0.4 0.6 1.5 0.91.3 2.5 MH (dN-m) 5 4.5 7.9 10.2 8.7 13.2 Shore A hardness and tensileproperties after press cure and post cure Shore A 45 52 60 65 65 70 Tb(MPa) 14.1 16.6 19.1 18.7 18.3 18.4 Eb (%) 640 690 690 300 410 345 ShoreA points 8 15 23 8 15 23 attributable to silica Shore A and tensileproperties after 2 weeks hot air aging at 190° C. Shore A 60 64 68 Tb(MPa) 10.9 12.2 12.3 Eb (%) 165 165 110 Shore A and tensile propertiesafter 3 weeks hot air aging at 190° C. Shore A 61 66 79 Tb (MPa) 6.5 5.75.8 Eb (%) 110 80 35

Example 16

Polyamide P3 was cryogenically ground so as to pass through a 60 meshscreen (0.31 mm opening). The ground polyamide was mixed with acrylatecopolymer A1 in a ratio of 40 parts by weight polyamide to 60 parts byweight acrylate copolymer using a Haake® Rheocord mixing bowl operatedat room temperature and 50 rpm rotor speed for three minutes. Thetemperature of the polymer composition remained less than 50° C. duringthe mixing process, so the polyamide did not melt. For comparison, thesame composition was produced via blend method E of Example 1, in whichthe polyamide becomes melted. Table 24 summarizes the blends produced.

TABLE 24 Composition B52 B53 % % A1 60 60 P3 cryoground 40 P3 pellets 40Mixing method Low temperature mixing High temperature bowl, polyamidenot Melted extrusion, polyamide melted Green strength (MPa) 0.3 0.4Compositions B52 and B53 were used to produce curable compositions CE41and E36, respectively, as shown in Table 25. After press cure and postcure, CE41 exhibited low tensile strength, equal to that of CE32, anunreinforced compound comprising acrylate copolymer A1. Composition E36,however, exhibited high tensile strength.

TABLE 25 Composition CE41 E36 phr phr B52 166.67 B53 166.67 Curative 10.6 0.6 Accelerator 1 1 1 Scorch retarder 0.5 0.5 Process aid 0.5 0.5AO-1 2 2 Cure response ML (dN-m) 0.5 0.6 MH (dN-m) 10.4 11.6 Shore Ahardness and tensile properties after press cure and post cure Shore A63 64 Tb (MPa) 2.1 14.8 Eb (%) 203 235

Example 17

Polyamide-filled acrylate copolymer compositions B54, B55, and B56 wereproduced on a 25 mm Berstorff twin screw extruder operating at 150 rpm.The barrel temperatures were set to 10° C. above the melting peaktemperature of the polyamide used in the blend. The blends werecollected and cooled to about 25° C. Compositions and green strength ofB54-B56 are shown in Table 26.

TABLE 26 Composition B54 B55 B56 % % % A1 75 A2 60 A7 75 P4 25 P5 40 P625 Green strength (MPa) 0.4 0.4 0.5Blends B54-B56 were mixed on a roll mill to form curable compositionsE37-E39, as shown in Table 27. Comparative curable compositionsCE42-CE44 were prepared from the same acrylate copolymers as E37-E39,but contain carbon black as the sole reinforcing filler. All the curablecompositions cure well and exhibit good properties after press cure andpost cure. However, after 2 weeks at 190° C. hot air aging, curedcompositions E37-E39 exhibit greater tensile strength and elongationthan the respective cured comparative compositions that comprise thesame acrylate copolymer and incorporate carbon black as a filler.Compositions E38 and CE43 comprise acrylate copolymer A2, which has ahigh level of copolymerized cure site monomer of about 1.3 mol %. As aresult, the cured compositions comprising A2 exhibit a greater tendencyto harden and embrittle during hot air aging than cured compositionsbased on acrylate copolymers comprising less than 1 mol % copolymerizedcure site monomer.

TABLE 27 Composition E37 E38 E39 CE42 CE43 CE44 phr phr phr phr phr phrB54 133.3 B55 166.7 B56 133.3 A1 100 A2 100 A7 100 Curative 1 0.6 1 0.60.6 1 0.6 Accelerator 1 1 1 1 1 1 1 AO-2 1 1 1 1 1 1 Process aid 0.5 10.5 0.5 1 0.5 N550 carbon black 30 45 30 Cure response ML (dN-m) 0.711.57 0.72 0.6 0.5 0.6 MH (dN-m) 8.4 13.9 8.3 5.8 7.8 5.3 Shore A andtensile properties after press cure and post cure Shore A 54 62 54 56 6759 Tb (MPa) 18.7 23.4 19 22.4 19.5 18.5 Eb (%) 360 230 340 625 360 515Shore A and tensile properties after 2 weeks at 190° C. hot air agingShore A 47 63 50 63 88 66 Tb (MPa) 8.5 10 9.4 5.8 7.5 6.1 Eb (%) 230 105220 120 40 110 Change as a result of hot air aging Shore A (pts) −7 1 −47 21 7 Tb (%) −55 −57 −51 −74 −62 −67 Eb (%) −35 −55 −35 −81 −89 −79

1. A polyamide-filled acrylate copolymer composition comprising A. apolymer blend composition comprising
 1. 40 to 90 wt. % of one or moreamorphous acrylate copolymers comprising a) at least 50 wt. %, based onthe total weight of the amorphous acrylate copolymers, of polymerizedunits of at least one monomer having the structure

Where R¹ is H or C₁-C₁₀ alkyl and R² is C₁-C₁₂ alkyl, C₁-C₂₀alkoxyalkyl, C₁-C₁₂ cyanoalkyl, or C₁-C₁₂ fluoroalkyl, and b) 0.3 molepercent-1.0 mole percent copolymerized units of a cure site monomerselected from the group consisting of unsaturated carboxylic acids,anhydrides of unsaturated carboxylic acids, unsaturated epoxides, andmixtures of two or more thereof; and
 2. 10-60 wt. % of one or morepolyamides having a melting peak temperature of at least 160° C.;wherein i) the polymer blend composition has a green strength of lessthan about 2 MPa as determined according to ASTM D6746-10, ii) the oneor more polyamides are present as a discontinuous phase in the polymerblend composition and iii) the weight percentages of the one or moreamorphous acrylate copolymers and one or more polyamides are based onthe combined weight of the one or more amorphous acrylate copolymers andone or more polyamides in the polymer blend composition.
 2. Apolyamide-filled acrylate copolymer composition of claim 1 wherein theone or more amorphous acrylate copolymers comprise copolymerized unitsof at least one monomer selected from the group consisting of alkylacrylates, alkyl methacrylates, alkoxyalkyl acrylates, alkoxyalkylmethacrylates, and mixtures of two or more thereof.
 3. A composition ofclaim 2 wherein the alkyl acrylate is an alkyl acrylate selected fromthe group consisting of methyl acrylate and butyl acrylate.
 4. Apolyimide-filled acrylate copolymer composition of claim 1 wherein atleast one of the one or more amorphous acrylate copolymers comprises acure site monomer selected from the group consisting of 1,4-butenedioicacids, anhydrides of unsaturated carboxylic acids, monoalkyl esters of1,4-butenedioic acid, and mixtures of two or more thereof.
 5. Apolyamide-filled acrylate copolymer composition of claim 1 wherein atleast one of the one or more amorphous acrylate copolymers additionallycomprises copolymerized units of an olefin.
 6. A polyamide-filledacrylate copolymer composition of claim 1 wherein at least one of theone or more amorphous acrylate copolymers comprises a cure site monomerthat is an unsaturated epoxide.
 7. A composition of claim 5 wherein theolefin is ethylene.
 8. A polyamide-filled acrylate copolymer compositionof claim 1 wherein at least one of the one or more polyamides isselected from the group consisting of i) polyamides formed by ringopening or condensation of aminocarboxylic acids and ii) polyamideshaving a melting peak temperature of less than 270° C. and an amine endgroup concentration of 60 meq/kg or less.
 9. A polyamide-filled acrylatecopolymer composition of claim 1 wherein the polymer blend compositioncomprises 50 to 80 weight percent of one or more amorphous acrylatecopolymers and 20 to 50 weight percent of one or more polyamides, basedon the total weight of the one or more amorphous acrylate copolymers andone or more polyamides.
 10. A polyamide-filled acrylate copolymercomposition of claim 1 additionally comprising an amine curative.
 11. Apolyamide-filled acrylate copolymer composition of claim 10 wherein theamine curative is a diamine carbamate.
 12. A polyamide-filled acrylatecopolymer composition of claim 10 wherein the amine curative is selectedfrom the group consisting of hexamethylenediamine, hexamethylenediaminecarbamate, and 2,2-bis[4-(4-aminophenoxy)phenyl]propane.
 13. Apolyamide-filled acrylate copolymer composition of claim 1 additionallycomprising a reinforcing filler selected from the group consisting ofcarbon black, amorphous precipitated and fumed silica, crystallinesilicas, clays, silicate minerals, titanium dioxide, wollastonite,antimony oxide, hydrated alumina, calcium carbonate, barium sulfate andmixtures thereof.
 14. A composition of claim 13 wherein the reinforcingfiller is carbon black or silica.
 15. A composition of claim 13 whereinthe filler has been treated with an organo-silane or a quaternaryammonium compound.
 16. A polyamide-filled acrylate copolymer compositionof claim 1 additionally comprising an antioxidant.
 17. A composition ofclaim 16 wherein the antioxidant is selected from the group consistingof aryl amines, phenolics, imidazoles, and phosphites.
 18. A compositionof claim 16 wherein the antioxidant is 4-aminodiphenylamine.
 19. Apolyamide-filled acrylate copolymer composition of claim 1 wherein atleast one of the one or more amorphous acrylate copolymers of thepolymer blend composition comprises 0.4 mole percent-1.0 mole percentcopolymerized units of a cure site monomer selected from the groupconsisting of unsaturated carboxylic acids, anhydrides of unsaturatedcarboxylic acids, unsaturated epoxides, and mixtures of two or morethereof.
 20. A polyamide-filled acrylate copolymer composition of claim1 wherein the at least one of the one or more amorphous acrylatecopolymers of the polymer blend composition comprises 0.5 molepercent-1.0 mole percent copolymerized units of a cure site monomerselected from the group consisting of unsaturated carboxylic acids,anhydrides of unsaturated carboxylic acids, unsaturated epoxides, andmixtures of two or more thereof.